MHIA’s PROP seminars keep MU-2 pilots safer

 - May 16, 2008, 11:24 AM

How many manufacturers sponsor regular owner/operator safety seminars on aircraft that went out of production 17 years ago? Mitsubishi Heavy Industries America (MHIA) does, and its biennial pilots review of proficiency (PROP) series has significantly reduced the accident rate on the twin-turboprop MU-2.

First sold in 1968, the MU-2 has, at best, a checkered reputation among pilots. A spate of accidents in the mid-1980s led to a resumption of the pilot seminars in 1994 (one series was held in 1982, not to be repeated). Since the seminars resumed, the accident rate for the MU-2 has held steadily in the middle of the pack for its class, according to MHIA statistics.

The two-day PROP seminars are conducted, under an MHIA contract, by Turbine Aircraft Services (TAS), of Dallas. Former MU-2 factory demonstration pilot Pat Cannon plans and conducts the seminars and acts as the master of ceremonies. Conducted at area hotels, the seminars feature executive-level amenities, all paid for by MHIA. In addition, product vendors have a room available to display their wares for MU-2 operators attending the sessions. Vendors include many of the authorized MU-2 service centers, interior shops, Honeywell (for engines and avionics) and other aftermarket producers of products aimed at MU-2 owners and operators. But the meat of the program is a series of presentations by representatives from MHIA, TAS, Honeywell Engines, Hartzell, SimCom (which now conducts MU-2 simulator training) and others.

This year’s series of seminars included sessions in Plano, Texas (April 5 and 6; 77 attendees); Windsor Locks, Conn. (April 12 and 13; 81 attendees); Orlando, Fla. (April 26 and 27; 54 pre-registrations at  press time); Nashville, Tenn. (May 3 and 4; 59 pre-registrations); and Scottsdale, Ariz. (May 17 and 18; 51 pre-registrations). Scheduled for May 15 and 16, just before the Scottsdale seminar, MHIA and Honeywell Engines are sponsoring a pilot-familiarization course on the TPE331, the engine that powers the MU-2. The fee for this course is $150 for PROP 2002 registrants, reduced from the normal cost of more than $1,000. All PROP seminars are free to registered attendees.

Attendees at PROP seminars include owner-operators and professional pilots who use MU-2s in a variety of roles. At the mid-April session in Windsor Locks, a contingent of 11 pilots from Thunder Airlines of Thunder Bay, Ontario, Canada, was on hand. Their company–led by Bob and Laurie Mackie, both of whom also attended the seminar–flies eight turboprops, including four MU-2s. Missions include 60- to 70 percent aeromedical transport, often flying from short gravel strips. One of Thunder Airlines’ concerns, voiced by Laurie– the company’s chief instructor–involves cabin windows that, under the stress of rough-field operations, have popped out and struck propeller blades in flight. TAS’ parts department responded by saying it is negotiating with new vendors for thicker windows.

Thunder Airlines pilots find the MU-2 a utilitarian workhorse, especially those equipped with the available Dash 10 conversion for its Honeywell TPE331s. The conversion to the later mark of the ubiquitous turboprop affords much improved takeoff, climb and cruise performance–up to 310 ktas from 270 ktas for the short-body MU-2s.

Product Support

MU-2 technical support from MHIA includes field service, engineering services, type-certification maintenance and FAA/NTSB coordination and air safety investigation (former MU-2 pilot Stephen Demko, now an NTSB investigator, was at the Windsor Locks PROP seminar). The field-service branch of the support structure includes 24/7 customer support, service-center support, reliability review of parts and components, service information review, vendor coordination and spare-parts assistance.

In its customer-support role, TAS handles publication distribution for MHIA for Airworthiness Directives, Service Bulletins and “service news” notifications less severe but nevertheless important service tips. TAS is also responsible for liaison for training programs; service-center program administration; vendor program administration; spare-part sales and distribution; customer contact; and the PROP seminars and other safety programs conducted in connection with NBAA and other organizations.

Icy Topic

The Windsor Locks PROP seminar began with an MU-2 icing video prepared by TAS. As part of an Airworthiness Directive, an MU-2 pilot needs to have seen the video to exercise the airplane’s authorization to fly in “known icing” conditions. PROP attendees who viewed the video filled out certification forms that were forwarded to the FAA to certify that they had indeed seen the video.

On-screen images primarily come from a series of in-flight icing tests performed a few years ago using a U.S. Air Force tanker converted to spray behind it a cone of dyed water. The tanker was used in icing evaluation tests for the ATR turboprop regional airliner following the infamous fatal icing accident in Roselawn, Ind. in October 1994. The severe icing that is most dangerous originates with so-called supercooled large droplets (SLD) of water. The droplets can be hundreds of times larger than droplets that cause less severe ice, such as rime.

With SLDs, the moisture splatters on the cold-soaked surface of the airplane and freezes on contact, often spreading aft beyond the reach of wing-leading-edge de-icing boots, especially on the underside of the wing. On MU-2s, SLDs can also cause ice accretion in the engine-intake area and on the horizontal stabilizer, sometimes leading to icing-contamination tail stall, particularly at high angles of attack, such as in the landing flare.

The added weight of the ice is not considered a serious problem for MU-2s. But the degradation of lift (due to changes in the airfoil shape) and the possibility of engine flameout from melting nacelle ice are greater concerns. At the PROP seminar, pilots were repeatedly warned of the danger signs indicating that severe icing could be at hand.

The signs include loss of airspeed by 20 kt or more; a decrease in rate of climb to 300 fpm or less; and unusually extensive visible ice on the undersides of the wings, nacelles, prop spinners or windshield. “If one of these symptoms is observed,” warned Cannon, “call ATC and get out of the icing condition; don’t let your airspeed drop below 180 kt; increase your speed by 10 percent if you can do so within operating limits; avoid abrupt movements of the controls; and do not use the autopilot. Disengage it if it is engaged.”

Cannon explained that the autopilot roll command induces a 25-deg bank, enough to invoke a stall if ice has deformed the wing shape and reduced efficiency. If roll is introduced, he said, lower the nose to increase speed to a safer range. Use of flaps should be avoided. The increased angle of attack could cause more ice to adhere to the wing’s underside.

With the decreased lift of an ice-contaminated wing, said Cannon, the MU-2’s stick shaker is no longer an effective warning indication of an impending stall. “The first you’ll know of the stall,” he said, “is a wing buffet followed by the nose dropping. Fortunately, the MU-2 has good stall behavior, even with an ice-contaminated wing. That was confirmed by tests with simulated ice shapes attached to the wing.” With all the emphasis on icing concerns, Cannon was compelled to emphasize that severe icing caused by SLDs constitutes less than 1 percent of icing encounters.

Following the icing video and discussion, programs included detailed presentations on aerodynamics by TAS’ Rick Wheldon; engine operations by Honeywell Engines’ Helmuth Eggeling; propeller operation and maintenance by Hartzell’s Keith Huffman; service information from TAS’ Jim Stermer; and an analysis of accidents by TAS’ Cannon. The latter concentrated on identifying the “error chain,” breaking it down into key components and attempting to tag which components led to a particular accident. This year’s PROP seminars included discussions of accidents at Albuquerque, N.M., Rifle, Colo., and Martha’s Vineyard, Mass. (see “Accident Recaps,” page 123). Though not all accidents have yet received an official probable cause from the NTSB, the PROP seminar opened the discussion among pilots as to what they thought were the chief contributing factors.

Day two of the seminar included a continuation of many of the topics begun on day one, with the addition of engine upgrade (Dash 10 conversion); declaring an emergency; maintenance test flights; oxygen emergencies, a SimCom program; and a second session of questions and answers, moderated by Bill White, a 20,000-hr MU-2 pilot.

Attending a PROP seminar could not be considered on a par with conventional introductory and recurrent pilot training, but the sessions are designed to present operators and service providers with a forum to discuss topics of common concern. The venue convenes technicians, vendors and aircraft owners for a true face-to-face interaction.