What”s Wrong With the MU-2?
By Fred George
What”s Wrong With the MU-2?
By Fred George
According to several of its operators, the Mitsubishi MU-2B is one
of the fastest, most fuel efficient, strongest and most responsive
handling general aviation twin turboprops yet built. With flaps
retracted, it has virtually the highest wing loading of any popular
twin turboprop, providing a smooth ride in turbulence and minimal
frontal area for reduced drag and efficient cruising. Fitted with
Honeywell (Garrett) TPE331-10 turboprop engines as standard or retrofit
equipment — the prototype MU-2, or A model, was fitted with twin
Astazous but did not go into production — the short-body MU-2B models,
including the Solitaire, will cruise as fast as 315 KTAS at 20,000
feet. The long-body models, including the Marquise, can fly faster than
305 knots. The MU-2B, without a doubt, provides more speed for the
dollar than any other general aviation turboprop on the resale market.
also able to fly slowly in general aviation airport traffic patterns
because it’s fitted with full-span, double-slotted Fowler flaps that
increase overall wing area by almost one-quarter when extended. The
MU-2B can slow down to 120 KIAS to sequence with other general aviation
aircraft on downwind. Vref speeds on final range from 100 to 110 KIAS,
depending upon landing weight. In many ways, the MU-2B flies like a
current-production light jet with turboprop engines.
Dick Allan, president of Internet Jet Sales, a well-known MU-2B
broker in the Northeast United States, says the aircraft’s jet-like
performance has special appeal to a special set of pilots, ones who are
notably different from those who fly more matronly turboprops. He
likens the aircraft to “a stanine test that separates fighter jocks
from bomber pilots.”
But Allan points to another part of the MU-2B population. He
believes the aircraft’s popularity with low-budget canceled check
transporters and all-night air freight operations is problematic since
they can afford to buy the airplane, but don’t have the money (or the
will) to invest in rigorous pilot training or top-notch maintenance.
That view is shared by FAA insiders. “The business model has
changed. It’s now migrated to the bottom-feeders in the air freight
industry,” said one FAA source. “We need to bring up pilot
qualifications to a level that the aircraft demands. And we may see
some recommended Service Bulletin and factory maintenance procedures
made into ADs.”
The MU-2B has been a dream-machine for the plaintiffs’ bar for
several years. Of the 800 or so aircraft that were built between 1967
and 1985, more than 200 have been involved in incidents or accidents,
according to NTSB statistics. The accident rate was particularly bad in
2004 and 2005, with a dozen-plus crashes and 13 fatalities. Overall,
its five-year accident rate from 2000 to 2004 was 3.17 per 100,000
flight hours, compared to 1.73 accidents per 100,000 flight hours for
that time frame among other popular turboprops, according to Robert E.
Breiling Associates. During the same five-year period, the Mitsubishi’s
fatal accident rate was 1.66 per 100,000 flight hours, or more than
triple that of popular turboprops, Breiling asserts. Since the
airplane’s entry into service 37 years ago, more than 200 people have
been killed in MU-2 accidents, trial lawyers say. Those statistics also
focused the attention of the FAA on the aircraft. About 400 MU-2B
aircraft are still in active service.
To understand how that history impacts fleet values, see this month’s 20/Twenty on page 112.
So, what’s wrong, if anything, with the MU-2? The answer depends
upon whom you ask. Few aircraft incite such polarized opinions as does
the MU-2. The two camps are divided primarily into folks who have flown
it or in it for years without incident, and those who have never gotten
in one and don’t intend to do so under any circumstances.
Among the current group of MU-2B foes are several members of the
U.S. Congress who have received letters from constituents with
relatives who have perished in recent Mitsubishi crashes. Many of these
letters request that the aircraft be grounded immediately by the FAA
and that a full investigation be launched as to why it’s so accident
prone. Some of those letters look very much like documents written by
trial lawyers because of their precise accident analyses, bar graphs
and inclusion of pilots’, passengers’ and even pets’ names for each
crash. It’s rare that heirs of crash victims independently undertake
such thorough accident history research and have access to so many
personal details of other crash victims, numerous sources told B&CA.
The letter writing campaign nonetheless has been effective. Members
of Congress are demanding action from the FAA to ground the aircraft or
at least mandate stringent standards for pilot training. The FAA, under
pressure from these lawmakers, recently concluded its fourth look at
the MU-2B, as we’ll discuss later in this report.
“This is a dangerous bird, with an extraordinarily high crash
incidence rate. We are not convinced that it’s ever been fully tested.
I think there’s a design flaw in the aircraft,” said Terry Van Keuren,
constituent advocate for Rep. Tom Tancredo (R-Colo.). Van Keuren said
he’s had several letters from constituents who are heirs and relatives
of people killed in MU-2 accidents in Colorado. He said he doesn’t
believe the FAA properly evaluated the Japanese-designed and -built
aircraft during the initial 1965 type certification, the follow-on 1984
Special Certification Review or the 1997 Fact Finding Focus Special
Certification Review related to approval for flight into known icing.
“It has a very thin, high-performance wing. It’s the only aircraft
in its class with spoilers [for roll control]. It has an inherently
wrong fuel system. And a Mitsubishi test pilot was told to lie about
its icing vulnerability [sic] in the Rickert [v. Mitsubishi Heavy
Industries] case,” he said. “It has a disturbing history of icing
problems, of prop problems and there’s a lot of sneaky stuff going on.
Too many things just don’t pass the sniff test.”
Van Keuren also said the engines have a tendency to “burp” (lose
power) and the NTSB is looking into aircraft problems related to power
interruption. Notably, NTSB accident analyses don’t appear to indicate
that the aircraft has an abnormally high, unexplained engine failure
He also claims the aircraft provides very little stall warning.
“There’s even a warning in the Flight Manual,” Van Keuren pointed out,
in reference to Mitsubishi’s caveat about fully stalling the aircraft
with one engine providing “lift producing thrust” that could cause a
“rapid rolling and yawing motion.” He did not mention that this would
be an unsafe maneuver in virtually any other high-performance twin
turboprop. It’s useful to note that the same section of the Pilots
Operating Manual also states that the aircraft’s stall characteristics
are “conventional in all configurations” and that a stick shaker warns
of the impending stall four to nine knots above stall speed.
“The airplane is just unsafe. Rep. Tancredo wants the aircraft
grounded or for the FAA to follow Mitsubishi’s recommendations for
pilot training,” said Van Keuren.
Although a former U.S. Air Force B-52 pilot with extensive flying
experience, Van Keuren admitted he’s never flown the MU-2. So when
questioned on technical details, rather than respond, he suggested
B&CA contact Robert Cadwalader, an 11,000-hour former Part 135
pilot and columnist for the Atlantic Flyer, a regional general aviation
publication. Van Keuren claimed that Calwalader was a leading industry
expert on the airplane. However, when we contacted him, Cadwalader said
he’d not flown the aircraft extensively and later clarified that to say
all of his MU-2B time was accumulated in an approved flight simulator.
Nonetheless, Cadwalader is cited by some trial lawyers as an authority
on the aircraft. They quote from his numerous columns in which he has
criticized the aircraft extensively.
“It simply doesn’t matter how good a pilot is — if he loses power
at low altitude [in an MU-2] he is going to crash,” Cadwalader asserted
in a recent issue of Atlantic Flyer. “An MU-2 with one engine out is a
very, very dangerous airplane and it can go out of control without the
pilot being able to stop it.”
When pressed for specifics, Cadwalader told B&CA that his
accounts of the aircraft were “apocryphal” rather than statistically
based. He asserts, for instance, that the NTSB mentions engine failure
or power loss due to undetermined reasons. Engine failure indeed has
been a contributing factor in many fatal MU-2B crashes, but the NTSB
has named it as the probable cause only in a handful of incidents. In
most engine failure events that led to fatal accidents, the NTSB has
placed primary blame on pilot error, according to our review of NTSB
accident statistics. The Safety Board investigator leading the review
of the December 2004 crash of an MU-2B-60 at Denver’s Centennial
Airport, for instance, told B&CA, “Certainly, that aircraft is very
capable of flying single-engine. Granted, you need to be on top of the
airplane and very attentive to airspeed [control].”
Cadwalader also claimed the FAA never retested the aircraft
adequately during the 1984 Special Certification Review. He said the
FAA’s pilots never flew it outside of the flight envelope published in
the Approved Flight Manual but offered no proof of that assertion.
He also claimed that the original FAA certification of the MU-2 was
tainted by the State Department’s putting political pressure on the FAA
on behalf of the Japanese, who became a strong U.S. ally during the
early years of the Cold War. That assertion was hotly contested by FAA
insiders who consider that statement an indictment of their
Cadwalader further notes that plaintiffs’ representatives are not
allowed “to witness or be involved in” MU-2 accident investigations.
But as a matter of practice, the NTSB and FAA only invite
representatives of the accident aircraft’s airframe and engine
manufacturers, plus a few other select parties with a vested interest
in the aircraft or operation, to participate in the investigations. The
NTSB often requests assistance from manufacturers to expedite fact
finding but limits their participation and normally bars their contact
with witnesses. Cadwalader views this exclusion of trial lawyers and
plaintiffs as a cover-up.
During the interview Cadwalader made several references to
observations by Donald Kennedy, Ph.D., a retired aerodynamics professor
from the University of Colorado at Boulder — and now based in Kihei,
Maui, Hawaii. As it turns out, Kennedy is frequently called as an
expert witness in aviation litigation cases on behalf of the
In one expert opinion letter about the MU-2B written for a
Denver-based trial lawyer, Kennedy cites 37 reference documents and
comes to several adverse conclusions about the aircraft. One opinion is
that the aircraft fails to meet FAA standards for controllability,
based upon its high accident rate and wing loading, which, he wrote, is
“well beyond the prudent standards of aircraft design . . .” Kennedy
also opined that the “choice of spoilers for roll control in a light
aircraft is a defective design and an unusual application.” Yet a third
opinion is “the choice of airfoils for wing and horizontal tail
surfaces were chosen to reduce drag at the expense of poor stall
characteristics in icing conditions. . . .”
These opinions are in direct contrast with the FAA’s conclusions in
the original and two subsequent special certification reviews of the
aircraft. Agency officials said that there’s “nothing wrong” with the
MU-2B’s fundamental design and that it meets or exceeds all type
certification standards that were in effect in 1965 when it was
undergoing its certification trials. One former NTSB investigator said
Kennedy was trying “to rewrite the laws of physics.”
However, trial lawyers have prevailed in numerous MU-2B product liability cases.
Generally, they question the FAA’s competence in approving the MU-2B
and insist that the FAA’s initial certification and subsequent
certification reviews were inadequate. NTSB conclusions, according to
them, are equally suspect. And they hold that any caveat in the
Approved Flight or Pilots Operating Manuals warning pilots not to
venture outside the published flight envelope is a tacit admission by
Mitsubishi Heavy Industries that the MU-2B is inherently unsafe.
When interviewing the aircraft’s critics, we heard lots of hyperbole
such as “when you use a [roll] spoiler, you lose all lift on that
wing;” and “the MU-2 lacks the controllability at slow speed during
single-engine operations;” and “below 153 knots, you can’t maintain
directional stability if you lose an engine. . . .” We figured we’d
find out for ourselves.
But we also concluded that there’s no way to change the minds of
MU-2B foes if they won’t accept a basic level of competency and honesty
on the part of the FAA and NTSB in the first place.
We spoke with several experienced MU-2B pilots who strongly dispute
the opinions expressed by the aircraft’s detractors. None believe
exceptional piloting skill is required to fly it safely. But none had
any illusions about the need for vigilance in the cockpit, the mandate
to operate the aircraft within the flight envelope and the critical
need for comprehensive recurrent training and good maintenance.
John S. “Jack” Broome of Oxnard, Calif.-based Broome Ranches has
been flying MU-2B aircraft for more than three decades, accumulating
more than 2,700 flight hours in type. He first soloed in 1935, later
became a military pilot and airline captain, and he served on the
NBAA’s board of directors for 20 years. He owned and operated Beech 18s
for 27 years before buying his first MU-2B in 1973. He hasn’t had an
accident in 70 years of flying.
He has forceful opinions about the MU-2B allegedly being unsafe.
“Going back years ago, folks said the same thing about the V-tail
Bonanza, Learjets and Aerostars.” He puts prime importance on being a
competent, well-trained pilot. “People can get out of a Cessna 310,
legally step into an MU-2B and say ‘I don’t need any training.’ Then
they get themselves into trouble.” That results in accidents, which in
turn, drive down resale prices and drive up insurance premiums.
“There are lots of good airplanes out there, but this one will do
300-plus knots on 80 gallons per hour. It will also slow down to 120
KIAS on approach. There’s just no way to get into trouble with the
airplane if you fly it by the numbers. For example, I don’t use full
flaps until I’m over the fence and slowing to final landing speed. I
don’t want any surprises; I’m too old for surprises,” he said.
Broome insists on undergoing rigorous recurrent training and has
high praise for Mitsubishi’s Pilot Review of Proficiency (PROP)
training program. “That makes the best pilots out of MU-2 pilots,” he
A veteran pilot with thousands of hours in DC-3s, DC-4s and Beech
18s, Broome claims that each of those aircraft was considerably more
difficult to fly than the MU-2B. “I’ve had ‘memorable landings’ in all
those aircraft,” he said, “but I’ve had no memorable landings in the
He thinks the MU-2B is a “pussycat’ and he wouldn’t sell the
aircraft unless he couldn’t fly it. Now 88, Broome still flies his
current MU-2B regularly.
Col. Frank Borman, the former Apollo astronaut, flew three models of
MU-2B aircraft during a 15-year period, accumulating a total of 3,500
hours flight time.
“They run very, very well and they’re most robust, built like
military airplanes,” he told B&CA. “It’s a solid, honest airplane.”
Borman said he underwent FlightSafety recurrent training yearly
while operating the MU-2 and attended the Mitsubishi-sponsored,
three-day PROP course. He believes other MU-2B pilots should do the
same, but that most just don’t get enough training. “If you’re a
relatively new multiengine pilot, if you lose an engine you’ll have
your hands full.”
The Las Cruces, N.M., resident believes that the recent pressure
from certain congressmen to force grounding of the aircraft is totally
unwarranted. “I don’t understand the criticisms of the aircraft. It
went through two FAA certification procedures, plus the most extensive
flight into known icing approval I can remember.”
Jack Jaax, an experienced, former Part 135 MU-2B charter operation
owner and chief pilot, echoed these comments. “It’s a great airplane,
mechanically and it has a high build quality. But you need to fly it by
the numbers.” Jaax flew the MU-2B on air ambulance and charter missions
for several years in the Southern California area. Well-known in San
Diego, Jaax recently sold his MU-2B charter operation and now flies a
locally based Beech King Air F90 for its owner.
Don Taylor, vice president of training at Eclipse Aviation, owns an
MU2B and says he “really likes the airplane. It’s fast, extremely well
built and the pressure vessel is really tight. It’s 15 knots faster
than a Twin Commander with the same engines.”
Having logged about 325 hours in the aircraft in less two years,
Taylor admits it flies differently than airplanes with aileron roll
control. He said it’s a “little disconcerting” in that it has a slight
tendency to keep rolling in a turn, lacking the spiral stability of
some other aircraft he’s flown.
“I think the main issue is training,” said another experienced MU-2B
pilot. “So many accidents have occurred in the Part 135 community among
those who haven’t had formal training. It’s all done in house. You need
frequent proficiency training in this aircraft and it needs to be
This pilot said he lost an engine on climb-out leaving a
Philadelphia area airport. “It was a non-event. The engine went
‘whoosh’ and NTS [negative torque sensing] reduced the prop pitch. I
checked the torque gauge and feathered the engine.”
The same pilot said the aircraft has somewhat of a split personality.
“It flies like a Patriot missile with the flaps up and a Cessna 172
with the flaps down.” At MTOW, for instance, the Marquise stalls at 105
KIAS in the clean configuration, but only 87 KIAS with flaps set to 20
degrees. Its 64000-series NACA airfoil also doesn’t provide much
aerodynamic stall warning, thus the need for a stall warning stick
shaker, a safety device commonly fitted to many jet aircraft.
Experienced MU-2B pilots emphasize the need to stay ahead of the
aircraft, particularly in the Window of Risk associated with takeoff
“Fly it with your left hand and think with your right hand,” one
cautioned. “On departure, don’t make any turns until you get it cleaned
up.” Gaining altitude is critical, the old pros say. Several cautioned
to keep the flaps extended until reaching 400 feet agl and never
touching the flap switch in a turn. They also said that it’s very
important to get the gear up as soon as a safe landing cannot be made
and you’ve established a positive rate of climb.
Flying stabilized approaches is equally important. Allow yourself
ample distance to get configured and stable, they recommended. Once you
get the gear down and flaps to 20 degrees on approach, 120 KIAS comes
up quickly. You can’t afford to get distracted, especially on “black
hole” approaches. Concentrate on the basics. Fixed shaft turboprop
engines can cause some inexperienced MU-2B pilots to confuse the sound
of high prop speed with high power, according to Broome. Airspeed
control is especially critical.
The consensus was clear from all with whom we spoke. Fly the MU-2B
as you would a jet, they advised. Use the same operational protocols,
fly it by the numbers and fly it with discipline.
“Amateurs should not be flying the airplane, ” said William Seaman, chief pilot at Flightpath Aviation.
And yet, Dick Allan of Internet Jet Sales says the MU-2B’s jet-like
performance pulls them in, attracting “people who don’t belong in it.”
He describes this group as “a very odd set of pilots — the fire
eaters, the sword swallowers and the lion tamers. All of them are like
bent nails in a can in your garage. When you need some, you look for
the least bent ones and then try to straighten them out before you can
We Fly the MU-2B-60
In late December 2005, Tom Berscheidt, president of Dallas-based
Turbine Aircraft Services (TAS), invited B&CA to fly a 1980
MU-2B-60 Marquise, s.n. 794, accompanied by chief pilot Pat Cannon. TAS
is under contract to Mitsubishi Heavy Industries to help support the
MU-2 and specializes in sales, service and parts for the aircraft. It
is closely associated with both Mitsubishi and Simcom and is a
co-sponsor of the PROP seminars.
Our mission profile consisted of a normal VFR takeoff from San
Diego-Montgomery Field, a climb to 7,500 feet for air work over Borrego
Springs and then a series of normal and simulated
one-engine-inoperative (OEI) takeoffs and landings at Thermal’s Jackie
Cannon started the preflight briefing by showing us a number of
inflight video clips that help dispel common misconceptions regarding
the aircraft. First, MU-2B foes often say that Mitsubishi’s use of
spoilers for roll control causes the entire aircraft to drop when one
deploys, rolling the aircraft about the centerline of the upwing
tiptank. The video, though, shows clearly that the aircraft rolls
crisply about its longitudinal access with virtually no adverse yaw.
Another video clip disproves the naysayers’ assertions that the
aircraft is uncontrollable at low speed with flaps extended and OEI.
The sequence was shot at 5,000 feet agl, with the landing gear down,
flaps extended to 20 degrees and aircraft stabilized and trimmed at 120
KIAS. One engine then is suddenly shut down. This is accompanied by a
momentary yaw and a slight roll into the dead engine. The pilot them
trims and stabilizes the aircraft while increasing power on the
operating engine to 100 percent torque. The aircraft remains fully
under control. A gradual climb is achieved at 125 KIAS at a mid-range
After landing gear retraction is initiated, the opening of the gear
doors causes a 50- to 100-fpm decrease in climb rate. Once the gear are
fully retracted, though, the climb rate increases substantially and the
aircraft begins to accelerate. The flaps are retracted to five degrees
at 140 KIAS, then fully retracted as the aircraft reaches 150 KIAS. The
pilot then accelerates to 154 KIAS, the best rate of climb speed at
Video clips also show the aircraft is fully controllable during
symmetric power stalls, with no tendency for wing roll-off at the stall
Cannon explained that we would repeat some of these maneuvers during
the demonstration flight, but at no time would he allow the aircraft to
be operated outside of the approved flight envelope. With that we
The external preflight of the MU-2B is conventional. Along with the
usual fluids, pressures and integrity checks, though, it’s essential to
check that the props are set at zero pitch, frozen in position on the
start locks. This assures minimum drag on the fixed-shaft engines
during start. It’s also important to extend the flaps and check the
rigging. The MU-2B has one flap motor and a series of interconnected
shafts and flex cables that drive flap jack worm screws. To ensure
proper operation, the flaps must extend symmetrically and exhibit no
evidence of binding.
Checking the fuel caps can be a challenge. Tall pilots, flying the
long body models, can step on the main doorsill and peer over the wing
to make sure the caps are secure. We prefer, however, to use a short
ladder to get a close-up view and tactile confirmation of the fuel
caps’ being secured. Folks flying short body models must use a ladder
because the entry door is under the wing.
Cannon mentioned that it’s also important to check operation of the
tiptank recognition lights, if the aircraft will be flown at night and
in icing conditions. The light shields collect ice quickly if icing
conditions are encountered. The tiptank lights make it easy to see the
ice accumulation, thereby warning the crew in time to activate ice
protection systems and execute an exit strategy from the adverse
weather. The aircraft we flew also was equipped with an optional ice
detection system, an addition we strongly recommend on any business
aircraft operated in icing conditions.
After a rash of icing-related accidents in the early 1990s, the
MU-2B underwent a thorough Fact Finding Focused Special Certification
Review of its approval for flight into known icing (FIKI) conditions.
After a full series of ice shape tests and also supercooled large
droplet (SLD) icing tests flown behind a water-spray tanker, the MU-2B
was shown to be fully qualified for FIKI by the FAA. However,
Mitsubishi added caveats to the flight manual that actually apply to
any aircraft flown in icing conditions: Maintain minimum recommended
speed, ask for priority handling by ATC to exit the conditions without
delay, avoid abrupt control movements, don’t lower the flaps and don’t
use the autopilot.
Serial number 794 had an empty operating weight of 8,260 pounds.
With two crewmembers, the BOW was 8,660 pounds. Filled with 1,900
pounds of fuel, the ramp weight was 10,560 and our computed takeoff
weight was 10,500 pounds. Using the flaps 20 degrees takeoff
configuration, the all-engine takeoff distance was 3,000 feet based
upon the airport’s 423-foot elevation, ISA+3ýýC OAT, 30.02 altimeter
and calm winds. Cannon recommended using a 102 KIAS rotation speed,
three knots above Vmca. This was two knots faster than the book value
Many useful charts have been eliminated from newer MU-2B manuals.
The original books provided accelerate-stop distance charts, OEI
takeoff distance charts for flaps five degrees and 20 degrees, and
maximum takeoff weight limited by OEI climb requirements. The FAA
directed those charts be removed from the manuals because they did not
conform to the GAMA standard and involved “demonstrated” data as
opposed to “approved” data. In our opinion, those charts should be
restored to the AFM. They provide useful information to pilots, even
though they’re not required for certification of this class of aircraft.
The new manuals, though, do provide OEI climb performance data for
the gear up, flaps retracted configuration. Assuming the same
conditions for our departure from San Diego-Montgomery Field, our climb
rate at 10,500 pounds would have been 650 fpm on one engine with gear
and flaps retracted. Experienced MU-2B pilots told B&CA that the
aircraft will climb satisfactorily at flaps 20 degrees under those
conditions, but only if the landing gear are retracted. If an engine
fails at rotation, “and continued flight is not possible,” the AFM
advises pilots to “land straight ahead.”
In lieu of providing such OEI takeoff data, the AFM now warns
“continued climb performance is not assured unless the landing gear are
completely retracted, the gear doors are closed and the flaps are at
five degrees or less.” Experienced pilots told B&CA that this
caveat is very conservative. They said that if the aircraft will climb
at 400 to 500 fpm in the clean configuration it will also climb
satisfactorily at flaps five degrees or 20 degrees, assuming the
landing gear are retracted.
Pre-start and pre-taxi procedures in the MU-2B aren’t as simple as
they are in most modern light jets. The MU-2B cockpit is very busy.
This is a Learjet 23-era design airplane and its systems are
characteristic of the mid-1960s. The instrument and side panels
seemingly are stuffed with as many switches, buttons, indicator lights
and gauges as a 1960s vintage military airplane. The voltage of each
battery, for instance, must be checked individually by using isolation
switches. Nickel cadmium batteries are standard and they’re recommended
for cold weather operations because of their superior starting power.
The aircraft may be fitted with lead-acid batteries for operations in
more temperate conditions.
AC inverter power is required for fuel and oil pressure indications,
fuel quantity indication and several analog avionics functions, so one
inverter must be operating prior to engine start. Stall warning systems
must be checked, along with fuel low level and empty aux tank
indicators, boost and transfer pumps, prop feather valve and NTS
functions. It’s important to note that most of these checks must be
performed in any TPE331-powered turboprop of that era, so the MU-2B
isn’t much more procedure intensive than a Cessna 441 Conquest, Merlin,
Cheyenne 400LS or Turbo Commander.
We’ll skip most of the preflight details, but it’s reasonable to
assume that pilots new to the MU-2B will spend several minutes in the
chocks running the various start and pre-taxi checks. The Mitsubishi is
a noisesome machine externally and internally (also characteristic of
its era), and active noise attenuating headsets are recommended.
With the condition levers in the taxi (minimum rpm) position, prop
speed is about 72 to 74 percent of maximum. Before taxiing, the
condition levers must be set to maximum rpm and the power levers must
be pulled aft from ground idle toward reverse pitch to release the prop
blade start locks. This allows the props to increase pitch and produce
forward thrust. Off the start locks, the condition levers are returned
to taxi. A properly set-up MU-2B won’t produce enough forward thrust at
ground idle to move out of the chocks, so the power levers must be
positioned between ground and flight idle to roll, even at
comparatively light taxi weights.
The MU-2B has excellent wheel brakes and somewhat sensitive,
direct-link nosewheel steering. The steering design allows the aircraft
to be taxied on one engine, if necessary, for repositioning on the ramp.
Once cleared for our VFR departure, we advanced the condition levers
to the takeoff/landing [maximum rpm] position and switched on auto
ignition to assure a relight in the event of a non-mechanical engine
failure. We advanced the power levers to 90-percent torque. Ram rise
during takeoff roll increases torque to 100 percent. We noted that
P-factor induced yaw is opposite most other turboprops. The engines
turn clockwise, but the props turn counter-clockwise resulting in a
right yawing moment with increasing thrust. It takes very little
pressure on the rudder pedals to counter this yaw because of the
effective nosewheel steering. But it takes some practice to reverse old
rudder-vs.-thrust-change habit patterns.
Rotation forces at 102 KIAS were considerably heftier than in some
turboprops because the main landing gear are well aft of the center of
gravity. Minimum rotation speed in the Marquise is never less than 100
KIAS because Vmca is 99 KIAS. Initial pitch force is much heavier in
short body models because the horizontal tail is closer to the c.g. and
the main gear are much farther aft of the c.g. With weight off the
wheels, pitch force was much lighter and we had to take care not to
over rotate beyond the recommended eight-degree nose-up attitude. The
aircraft quickly accelerated through 120 KIAS.
With a positive rate of climb, we retracted the landing gear. That’s
a comparatively long process. It takes about 14 seconds for the first
10, and the drag from the gear is considerable. After the gear were
fully retracted, the aircraft rapidly accelerated to 150 KIAS and we
retracted the flaps. As the large area Fowler flaps retract, it’s
necessary to increase pitch attitude by four degrees as the flaps move
from the 20 degrees to five degrees position. Then pitch attitude must
be increased by another four to five degrees as the flaps retract from
five degrees to flaps up. Think Falcon 10, in terms of flap position
vs. pitch attitude characteristics.
We began an eastward VFR departure and reduced power without delay
to maintain 200 KIAS below the floor of San Diego’s Class B airspace.
Once clear to the east, we climbed to 7,500 feet and rapidly
accelerated to 250 KIAS, the aircraft’s Vmo.
Checking the aircraft’s handling qualities, we were surprised by the
almost total lack of rudder input needed to maintain coordinated flight
when rolling left and right, even with full control wheel deflection.
The spoilers prevent virtually all adverse yaw, but lateral control
forces are considerably heavier than in most turboprops that use
ailerons for roll control.
We slowed to 180 KIAS, the Simcom recommended speed for steep turns.
Setting about 60 percent torque, we rolled into a 45-degree left turn,
then a 45-degree right turn. The pitch force required to maintain
altitude was moderate.
The demo profile next called for an approach-to-stall series. We
again noted a conservative warning note in the AFM that says “Up to 560
feet of altitude loss can be expected in recovery from a full stall.”
We reduced torque to 20 percent. As we slowed the aircraft in the clean
configuration at a weight of 10,200 pounds, we trimmed to about 130
KIAS and then just maintained altitude with increasing back pressure on
the yoke, decelerating at about one knot per second. At 100 KIAS, the
stick shaker activated. We added thrust and recovered with no loss of
control along with very little altitude loss.
We then set up for an approach turn stall by extending the flaps 20
degrees and trimming to 120 KIAS. Again we noted the need for eight to
10-degrees nose-down pitch change as the flaps moved from clean to 20
degrees. We rolled into a 20-degree left bank, reduced power and slowly
decelerated. When the stick shaker fired at 83 KIAS, we leveled the
wings, added thrust and flew out of the maneuver. Again the aircraft
suffered no loss of composure and lost just 50 to 100 feet of altitude.
So what about that caveat about losing 560 feet when recovering from
a full stall? Later in the flight, we slowed the aircraft in the clean
configuration until the stick shaker fired and then just continued to
increase back pressure on the yoke. As one expects in an aircraft with
a 64000-series wing, there was very light airframe buffet prior to the
full stall, highlighting the need for the artificial stall warning
system. At the full stall, the nose started to rock and then fall. We
persisted in holding back on the yoke. There was a little wing roll
that was easily countered with opposite roll spoiler. We held back on
the yoke and kept the aircraft fully stalled for several seconds,
maintaining wings level with roll spoiler control alone, but being
careful to keep the ball in the center with rudder control.
The aircraft’s stall behavior reminded us of a Falcon or a Learjet
45. We could not make it lose its composure during the maneuver.
However, when we’ve attempted the same maneuver in some other popular,
aileron-equipped turboprops in the past, we experienced considerably
more exciting results. Abusing aircraft with NACA 23000-series wings
during stalls just invites the onset of a spin.
Recovery from this maneuver in the MU-2B, in contrast, consisted of
reducing angle of attack and adding thrust. And, yes, we lost 500-plus
feet during the recovery because of the abuse we heaped on the
airplane. But it never bit back with a nasty surprise. It’s too bad
that we didn’t have time for a full stall series with the flaps
extended to various positions.
Cannon then demonstrated the effects of losing an engine in flight.
While we flew the aircraft at 150 KIAS, he switched the run-crank
switch to the off position. The negative torque system responded by
reducing prop pitch on the affected engine until the prop was slowly
windmilling. There was momentary yawing as NTS caught up with the power
failure. Cannon pulled the condition lever to feather, which caused the
blades to streamline. He also moved the power lever to maximum, the
procedure called out by the AFM. This ensures that all oil pressure is
relieved from the prop controller and that the spring in the hub fully
feathers the blades.
We trimmed the aircraft hands off first by using the trim ailerons
to neutralize the need for roll spoilers and then by using the rudder
trim to eliminate the need for asymmetric rudder pedal pressure. It’s
important to trim the aircraft in roll because a deployed roll spoiler
will reduce climb performance by 100 to 150 fpm. It’s also important to
keep the ball in the center, maintaining coordinated flight. Failure to
do so results in substantial roll into the dead engine. Cross
controlling the aircraft with roll spoiler and not enough rudder during
engine-out maneuvers just ruins its climb performance.
We slowed the aircraft to 140 KIAS and performed a series of steep
turns both away from and into the dead engine. We added sufficient
thrust to maintain speed in a 45-degree bank turn into the dead engine
and found no loss of composure, no controllability difficulties.
We then headed to Thermal for pattern work and Cannon restarted the
right engine. Cannon positioned the stop-run-crank switch to “run” to
arm auto-ignition and fuel flow. Air start must be done by windmilling
the engine because the electric starter could never overcome the
airloads of a feathered prop on a fixed shaft engine. The condition
lever, when moved from “emergency stop [feather]” to “taxi,” has no
effect on prop pitch because without the engine turning, there is no
oil pressure for prop control.
TPE331 engines, as a result, have an “unfeather” function that
requires use of an auxiliary electric oil pump. When activated, the
pump ports oil pressure to the prop, thereby reducing pitch and causing
it to windmill, assuming the condition lever is in the “taxi” to
“takeoff” range. The unfeather switch must be held until the engine
windmills to 30 percent rpm. As light-off occurs, the engine will
continue to accelerate, start to generate oil pressure and drive the
prop to the desired position. As thrust is restored, again trimming the
aircraft in roll and yaw is imperative. The MU-2B is a trim-intensive
airplane, one that rewards precise pilot technique and one that doesn’t
tolerate sloppy airmanship.
We set up for a left base and straight-in approach to Runway 35 at
Thermal at a weight of 10,000 pounds. Based on using flaps 20 degrees,
the computing landing distance was 2,750 feet, assuming a 1.3 Vs
landing speed. The first landing was flown at 20-degrees flaps at a
speed of 120 KIAS on approach, using about 20 percent torque, until we
approached the airport boundary. We slowed to the 105 KIAS Vref over
the threshold and reduced power to flight idle. The engine fuel flows
and prop pitch of this airplane were fine-tuned by Tulsa-based
Intercontinental Jet Corp. and they were spot on. Each engine
stabilized at 17 degrees torque, very close to zero thrust. The
aircraft settled down to the runway with the aplomb of a light jet.
At touchdown, we increased back pressure on the control wheel
smartly to prevent the nose from slamming down, moved the power levers
to ground idle and flew the nosewheel down to the surface. At that
point, we moved the power levers to reverse and the aircraft slowed to
Taxiing back to Runway 35, we flew a second circuit to a full stop,
this time using flaps 40 degrees for landing. The aircraft pitch
attitude is considerably more nose down using this flap configuration
and, ironically, AFM approach speeds actually are higher than at flaps
20 degrees because the book requires use of a 1.5 Vs landing speed. The
net result is virtually the same landing distance because the
additional drag slows the aircraft quickly in the landing flare with
power to flight idle.
Our next takeoff was at flaps five degrees. Cannon said we would
“lose” an engine on departure. On takeoff, we rotated at 105 KIAS,
about four knots above the recommended AFM speed and accelerated to 120
KIAS. At about 100 feet agl, about 10 seconds into gear retraction and
with all gear doors open, Cannon pulled back the right engine power
lever to flight idle. We responded by pushing hard on the left rudder
and countering the wing roll with spoiler. OEI climb performance indeed
was sluggish until the landing gear fully retracted. It then improved
to 300 to 400 fpm while we used differential trim aileron to eliminate
the need for roll spoiler input and put in plenty of rudder trim to
counter pedal pressure. After the aircraft was fully trimmed, it
climbed at 400 to 500 fpm and continued to accelerate. At 150 KIAS, we
retracted the flaps completely and continued to accelerate to the 154
KIAS blue line, best OEI climb speed. Climb rate exceeded 650 fpm at
that point. Meanwhile, we were quite busy retrimming the airplane in
pitch, roll and yaw during the level-off and subsequent asymmetric
Continuing with the simulated OEI emergency, we flew downwind,
delaying extension of gear and flaps to 20 degrees until we were on
extended base leg. We turned to final, slowed to 120 KIAS and made the
commitment to land. Landing technique was almost identical to the
all-engine landing, as we slowed to 104 KIAS over the threshold. Light
use of prop reverse and plenty of differential braking and rudder to
counter the resulting yaw moment kept us near centerline as we slowed
to taxi speed.
Cannon positioned the flaps to 20 degrees for another simulated OEI
departure. We used the same takeoff technique and speeds. Cannon pulled
back on the right engine power lever at 100 feet agl about 10 seconds
into the gear retraction cycle. OEI climb performance was lackluster,
but controllability was excellent. Once the landing gear were fully
retracted, the aircraft climbed at 200 to 300 fpm as we accelerated to
140 KIAS. At that point we retracted the flaps to five degrees, rotated
four more degrees nose up and climb performance increased to 500 fpm.
At 150 KIAS, we cleaned the wing and accelerated to blue line.
With all engine power restored, we headed to San Diego-Montgomery at
redline. SOCAL approach gave us priority over other arriving aircraft
because of our speed advantage. We touched down one hour, 37 minutes
after departing Montgomery Field.
Risky Airplane or Risky Pilots
Few multiengine airplanes we’ve flown demand more skill and
proficiency than the MU-2B. The Learjet 23, Citation X, CRJ700 and Saab
2000 readily come to mind as similarly demanding aircraft, but to fly
as PIC in any of them one needs type ratings and annual proficiency
While the MU-2B is more demanding to fly than most business aviation
turboprops, we encountered no nasty surprises or untoward handling
qualities in any part of the low-speed flight envelope, with one or
both engines operating, during our brief demo flight. We never had to
assume the role of fire-eater, sword swallower or lion tamer — or
experimental test pilot — to keep the MU-2B-60 under control. We
concentrated on directional control, airspeed control and trim control
while closely following AFM procedures, under the watchful eye of
Aircraft performance, though, was severely degraded when flown out
of trim during simulated OEI operations. Trim this machine in all three
axes in any regime, so that it will fly hands off, and it will perform
better than most general aviation turboprops at both low and high
speeds, on one or two engines.
It’s critical that the aircraft be properly maintained, specifically
regarding rigging of the engines, props and NTS functions. If NTS fails
to function properly during an engine failure after liftoff, the
aircraft could be quite a handful to control until the condition lever
of the affected engine is moved to the emergency stop (feather)
position. This is another reason why the pilot must perform the NTS
ground checks every day before the first flight.
Single-engine takeoff and climb performance in the MU-2B is
naturally limited by weight, altitude and temperature. Assuming
standard day conditions, if you depart at MTOW, using either flaps five
degrees or 20 degrees and lose an engine at 125-plus KIAS with the gear
retracted, you’re virtually guaranteed a satisfactory OEI climb rate
while the aircraft accelerates to the 150 KIAS flap retraction speed.
Below 125 KIAS and with gear down, you may have to pull back the
power, slow to 105 KIAS and land straight ahead. Old pros say you’ll
need 4,500 to 5,000 feet of runway to stay on the pavement if you lose
an engine just after liftoff and abort the takeoff.
Departing B&CA’s 5,000-foot elevation, ISA+20ýýC airport, we
recommend loading the Marquise to no more than 10,250 pounds and using
the flaps five degrees configuration to assure a positive OEI rate of
climb once the gear are retracted. Under these conditions, the MU-2B
should climb at 500 fpm on one engine after accelerating to 150 KIAS
and retracting the flaps, according to the AFM. But if the aircraft
suffers an engine failure with the gear down or in transit, you may not
be able to maintain a positive rate of climb, especially since it takes
14 seconds for the gear to retract completely. Again, plan on
maintaining directional control and land straight ahead if the aircraft
won’t climb on one engine.
With all engines operating, gaining altitude is more important than
accelerating, according to experienced MU-2B pilots. Get the landing
gear up with a positive climb rate and when you’re out of runway, they
say. The AFM recommends climbing at best all-engine rate of climb
speed, using 120 KIAS for flaps five degrees and 113 KIAS for flaps 20
Vyse speeds are increased respectively to 140 KIAS and 135 KIAS,
according to the AFM. If an engine fails after you’ve reached 400 feet
agl, it’s a lot easier to trade a little altitude for airspeed to
accelerate to the 140 KIAS minimum flap retraction speed, the MU-2B
pilots suggested. Some MU-2B pilots recommend climbing to 1,000 feet
agl before accelerating and retracting the flaps. They also say they
never move the flap switch in a turn to guard against flap asymmetry.
The MU-2B has had two Airworthiness Directives related to flight
into known icing conditions, but they’re not focused on the aircraft.
Rather, they’re aimed at the pilots. AD 2003-22-07, along with AD
97-20-14, which it supersedes, requires specific pilot training before
they fly the aircraft into known icing conditions. The latest AD
requires pilots to view a video that contains critical information on
how to recognize the onset of severe icing conditions and how to use
ice protection systems effectively. The ADs were issued because of “an
increased chance of icing-related incidents or accidents of the MU-2B
series airplanes due to pilot error” [emphasis added]. Recurrent flight
into known icing conditions training is required at 24-month intervals.
Once you’ve neared your destination, we advise flying approaches in
the MU-2B at typical light jet speeds, not typical turboprop speeds.
Fly no slower than 150 KIAS with a clean wing. With flaps extended to
five degrees, 140 KIAS is the recommended speed. At flaps 20 degrees,
use 125 KIAS in the turns and no slower than 110 KIAS on final approach
until you cross the runway threshold.
In flight, when the power levers are pulled back to flight idle, the
aircraft shouldn’t suffer a sudden loss of lift from flat pitch or
asymmetric drag. If it does, the props and fuel flows are not rigged
Pilots must truly take command of the MU-2B, especially when it
comes to grounding it for maintenance discrepancies. This aircraft can
be most unforgiving to those who defer squawks. If you can’t afford to
fix it, ground it.
Upcoming Mandate for Formal Training
Mitsubishi Heavy Industries has been requesting that the FAA mandate
formal training in the MU-2B since the early 1990s, including
advocating the need for an MU-2B type rating. But until the recent
spate of crashes and resulting pressure from U.S. Congress, the agency
has been reluctant to increase the regulatory burden on operators. A
recent analysis of MU-2B fatal crashes, though, indicated that only one
or two of the pilots killed successfully completed formal, third-party
That’s about to change. The most recent review of accidents by the
FAA found nothing wrong with the aircraft. Pilot error, in contrast,
pointed to a glaring lack of standardized, formalized training. As a
result, the FAA convened a Flight Standards Board, under the direction
of Johnathon Vetter, in the Wichita Aircraft Evaluation Group, to
evaluate the need for better training.
Vetter’s FSB team published its draft recommendations on Dec. 16,
2005, using the regulatory guidance of AC120-53, “Crew Qualification
and Pilot Type Rating Requirements for Transport Category Aircraft
Operated Under FAR Part 121.” The upshot is that the FSB recommended
airline-quality Level E initial training, such as that normally
required for a type rating, for pilots new to the MU-2B. Annual Level C
recurrent training, using a specific syllabus, also is recommended.
Requalification Level C training should be undertaken by pilots who
have flown the aircraft in the past two years, but haven’t undergone
recurrent training. Differences training will be required when
transitioning from certain models of short- and long-body models.
The FSB defines specific requirements for both ground and flight
training syllabi, along with areas of special interest and emphasis,
such as stall recognition, crosswind landing technique, single-engine
operations and flight into known icing conditions.
The FAA’s top brass in Washington has made the upgrade of MU-2B
training a priority issue. While they’re adamant about not making a
knee-jerk reaction to the recent pressure from Congress, they do plan
to issue a formalized training plan for MU-2B operators by the end of
the first quarter of this year. It’s doubtful that a type rating will
be required for the MU-2B, but most of Mitsubishi Heavy Industries’
training syllabus could become mandatory. This one-level-of-training
mandate would even out differences between third party training
providers such as Reese Howell and Simcom, and in-house training
provided by Part 135 operators and some private contractors. Watch the
Federal Register for a Notice of Proposed Rule Making in the next 30 to
The folks at the FAA’s Aircraft Certification Service also reviewed
the aircraft in the past several months, but they’re convinced that
there’s nothing faulty with the basic design, especially after three
rounds of certification activities.
Already, some Part 91 MU-2B operators are calling the FSB
recommendations “overkill,” anticipating a significant increase in
training expense and hassle because of the Part 121 approach to pilot
training. But just look at the accident statistics.
Dick Allan says of the MU-2B, “It’s so easy to fly that it breeds
complacency.” He believes that this higher level of pilot training will
slash MU-2B mishaps in half. We agree. The primary reason that so many
MU-2B aircraft crash can be found directly behind the control yoke, in
We’re looking forward to undergoing a complete Level E initial
training course in the MU-2B and then getting more experience in the
aircraft. The Marquise reminded us a little of our first experience in
the Learjet 23 in the late 1970s. It was both exhilarating and
illuminating. We could hardly wait to fly it, but only after thorough
QUALITY AIRPLANE MAINTENANCE IS CRITICAL
Bob Kidd, head of Tulsa-based Intercontinental Jet Corp., has no
illusions about the painful learning curve associated with the MU-2B’s
entry into service decades ago. It had multiple propeller and
prop-coupler failures, a resonant vibration that cracked prop blades
and plenty of engine failures. But now the aircraft is a mature design
and it’s as reliable as any general aviation turboprop — if it’s
Fine-tuning the flight idle fuel flow and prop governor performance
is high on Kidd’s list of must-do maintenance items. He believes that
Honeywell (nee Garrett Aviation) Service Information Letter P331-141
that describes adjusting the functioning of the prop governor in
relation to both the underspeed and overspeed fuel governors needs to
be made an Airworthiness Directive. Every time work is performed on a
propeller, prop governor, engine or fuel control, a post-maintenance
flight check should be done to check proper flight idle fuel flow and
torque, along with prop blade angles.
Kidd also believes the FAA should issue an AD requiring a specific
procedure to rig the flaps and check for proper flex shaft and
worm-gear box functioning. If the system is out of adjustment, the
flaps can bind and/or extend/retract asymmetrically. That can degrade
lateral control to the point at which the aircraft becomes dangerous.
Honeywell issued a mandatory Service Bulletin requiring that prop
shaft couplers be replaced with modified versions that are more robust.
Kidd believes this SB should be made an AD to prevent the possibility
of prop coupler failure, an event that has caused some fatal accidents
according to NTSB records.
Early aircraft have three-piece wings. The outer sections are
attached with hardware fittings, including barrel nuts that should be
inspected, if not replaced, at 7,500-hour intervals. This maintenance
requirement is often overlooked by some MU-2B operators, according to
There’s also a one-time inspection requirement to check for
indications of tiptank bracket overload. Kidd claims that two-thirds of
the fleet has never undergone this critical inspection.
But he was quick to add he believes that the vast majority of MU-2B
accidents are caused by pilot error, especially if folks don’t abide by
Reprinted from the February 2006 issue of Business & Commercial Aviation magazine.