CHI95FA071

The private pilot declared an emergency while at 16,000 feet in VFR conditions overhead the 9,000 foot runway. During the descent he stated his engine ran rough, then smoothed out. Approximately 4,000 ft AGL he stated he 'had a major problem...coming down.' Witnesses described the airplane in a steep descent, then entering a spin at approximately 1,000 ft AGL. The airplane impacted 3/4 mile short of the runway. Testing revealed the crankshaft failed in 2 places, both with areas of fatigue cracking. The fatigue origin was subsurface, the shaft was machined, not forged, and had an estimated 150 to 200 hours in operation. No other discrepancies were found with the airplane.

History of flight

On January 21, 1995, at 1537 central standard time, a Questair- Venture, N4QV, operated by Condominium Insurance Specialists of America, Inc., of Arlington Heights, Illinois, impacted level terrain 3/4 mile southeast of runway 31R at Des Moines International Airport (DSM), Des Moines, Iowa, and was destroyed.

The two private pilot occupants received fatal injuries, and a post-crash fire occurred.

The flight was conducted under 14 CFR Part 91, and was en route from Palwaukee Airport (PWK), Palwaukee, Illinois, to Cheyenne, Wyoming, on an instrument flight plan. Visual meteorological conditions existed at the time of the accident. The airplane was cruising at 16,000 feet above mean sea level (msl), when the pilot declared an emergency and requested landing at DSM. During the emergency descent, the pilot stated he would be making a "dead stick landing."

Several witnesses described the airplane descending in a spin immediately before impact, and a fireball occurring after impact.

Post-crash inspection revealed no indications of engine rotation at impact. Disassembly of the engine revealed the crankshaft broken in two locations.

Personnel information

The 43 year old private pilot had approximately 2,450 hours of total flight time. He had privileges for single and multi engine airplanes, and an instrument airplane rating. He held a valid Third Class medical certificate, with no limitations. He was the designer, builder and primary machinist of the experimental powerplant. He held Aircraft Repairman certificates with the privileges of FAR 65.103 for engine assembly, machining and accessory, and for inspection of experimental aircraft make Questair Venture serial number 102, and Questair Spirit serial number 12.

The 60 year old private pilot passenger was the owner of the company which produced the Questair airframe kits. He had accumulated approximately 2,300 hours of flight time. His private pilot certificate included privileges for single engine airplanes and instrument airplane. He held a valid third class medical certificate with the limitations of "must wear corrective lenses while flying."

Aircraft information

The experimental airplane was a QuestAir Venture, serial number 43. It was equipped with a German made M & T, 3 bladed, composite propeller, model number MTV-9-D, serial number 93216. Each wet wing held 44.5 gallons fuel in 2 tanks, located in the inboard half of each wing, one in front of the other.

The airplane was equipped with PMA-550-TTV engine, serial number 1012. Based upon a Teledyne Continental Motors (TCM) 550- series engine, the PMA-550-TTV, is a twin turbocharged, 550 cubic inch displacement, 6 cylinder, fuel injected, reciprocating engine rated at 350 horsepower at 2,700 rpm. The accident engine was equipped with a combined electronic and single magneto ignition system. The engine was manufactured by Improved Aircraft Engines, Inc., dba Precision Made Airparts (PMA). The pilot was the chief designer and engineer for the engine.

The company dba, PMA, is not synonymous with the more commonly used term PMA as applied to manufacturers by the Federal Aviation Administration. The FAA issues a Parts Manufacturers Authorization (PMA) for certified aircraft parts. This does not apply to the experimental application of the Improved Aircraft Engines, Inc., components discussed in this report. Throughout this report, the term PMA will refer to the manufacturers dba, not an FAA authorization.

Designated as an experimental engine, it consisted of both modified components from certificated engines, and original PMA components (specifically the crankshaft).

At the time of the accident, only 3 technical persons were employed at PMA; the pilot, the pilot's son, and a third machinist. In building the PMA-550-TTV engine, Carillo connecting rods were utilized. The crankshaft connecting rod journals had to be machined to accept the smaller diameter rods, regardless of whether the crankshaft was from TCM or PMA. A PMA spokesman stated to the Safety Board that PMA had attempted to forge crankshafts, but had been unsuccessful. As a result, the process of completely machining a shaft from a solid steel billet was used.

According to PMA, no PMA manufactured crankshafts were produced until October of 1994. Further statements were made to the Safety Board that engine s/n 1012 was assembled and installed in N4QV in March-April 1994. Safety Board metallurgical and dimensional inspection of the failed crankshaft established that the shaft conformed to specifications provided by PMA, and did not match TCM crankshaft specifications.

The airplane owner agreement to purchase a PMA-550-TTV engine was drafted December 23, 1992, and accepted January 8, 1993. The construction work order for PMA-550-TTV engine s/n 1012 was opened on January 8, 1993. Invoice #952.868 dated August 9, 1993, showed the engine completed, with a partial payment due. A second invoice, dated December 24, 1993, showed engine s/n 1012 completed, with no payment due.

Records indicate that engine s/n 1012 was installed in aircraft s/n 43 on June 27, 1994. No record of the crankshaft having accrued operating time prior to this could be found.

All components installed appeared to be marked with the same serial number as the crankcase, ie; 1012. The exception to this was the crankshaft itself, which was identified as s/n 1008. Engine serial number 1008 was manufactured in the PMA facility during the period July 23, 1992, to December 1992, and delivered to its owner in February 1993. It was returned to the factory for inspection due to being inactive without preservation in January 1994. Engine s/n 1008 was disassembled, cleaned, and reassembled between January and March 1994.

The periods of overlap at the factory between engines 1008 and 1012 were December 1992, to February 1993, and again between January and March 1994. It could not be determined if both engines were actually disassembled at the same time. Disassembly and inspection of engine s/n 1008 in April 1995, revealed a modified TCM crankshaft with no identifying serial numbers visible.

The main landing gear and flaps were operated by a common electric motor, and the nose landing gear was operated by an independent electric motor. Electrical power sources were the 24V 60 amp alternator and battery.

Serial number 43 was registered as having been built by Roger Bacon. An interview with the registered builder indicated that serial number 43 had been destroyed in an accident in Florida prior to 1994. During the interview, Mr. Bacon stated that the data plate he had attached to the airplane he built was hand etched. The data plate, exhibiting serial number 43 which was attached to the accident airplane was machine stamped. Mr. Bacon further stated that he had an outboard piece of the wing from the airplane he had built, and that he did not know who had rebuilt serial number 43, or manufactured a new data plate. Registration records showed that serial number 43 was transferred from Roger Bacon to Condominium Insurance Specialists of America on March 11, 1992. It is unknown whether this was a transfer of the actual aircraft, or a paper transfer of the serial number.

Work order entries showed the following repairs having been completed by Windham Aviation, Inc., of N. Windham, CT, Repair Station #FUKR-043E, on June 27, 1994:

"Repair s/n 43 Questair Venture model M-20 by replacing the following assemblies: 1. Fuselage Fast Build Que-2000076-1 2. Right Wing Fast Build Ques-2010068-1 3. Left Wing Fast Build Que-2010068-2 4. Stabilizer Fast Build Ques-2020024-1 5. Elevator Fast Build Ques-2021023-1 6. Vertical Tail Fast Build Ques-2025021-1 7. Rudder Fast Build Ques-2026022-1 8. Canopy Tinted Ques-2006001-2

The same entry shows installation of a PMA-550-TTV engine, and