N469CC

HISTORY OF FLIGHT

On August 6, 2011, at 1700 Eastern Daylight Time, a PA-46-310P, N469CC, was substantially damaged during a forced landing at the Curtis L. Brown Field Airport (EYF), Elizabethtown, North Carolina. The certificated airline transport pilot and his passenger were uninjured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal local flight conducted under Title 14 Code of Federal Regulations Part 91.

According to the pilot, he departed EYF after topping off the fuel tanks. While climbing through approximately 1,100 feet above mean sea level and turning from the crosswind leg of the traffic pattern to the downwind leg of the traffic pattern, the engine started making a "whining" sound. The pilot then began to "move the throttle around." The engine however did not respond. It then lost power, and the airplane began to descend. The pilot then turned towards the runway and feathered the propeller. He kept the landing gear up until "the last second" so that he would make the runway. Once he was assured that he would make it back to the runway, he put the landing gear handle in to the gear down position. The landing gear however, still had not fully extended when he touched down on the runway. The airplane then skidded on its belly down the runway and came to rest.

PERSONNEL INFORMATION

According to FAA records, the pilot held an airline transport pilot certificate with ratings for airplane single-engine land, airplane single-engine sea, airplane multi-engine land, and instrument airplane. He also held flight instructor ratings for airplane single-engine and instrument airplane. His most recent FAA second-class medical certificate was issued on March 22, 2011. He reported that he had accrued 4,930 total hours of flight experience, 326 of which were in make and model.

AIRCRAFT INFORMATION

The accident aircraft was a six-seat, single-engine, low wing, pressurized airplane of conventional metal construction. It was originally manufactured by Piper Aircraft in 1984 as a PA-46-310P.

It was equipped with retractable landing gear and was the 3rd airplane converted to a JetProp DLX when it had its original engine replaced in 1998 with a 580 shaft horsepower Pratt & Whitney Canada (PWC) PT6A-34, turbo propeller engine.

It could operate at an indicated airspeed of 260 knots at 27,000 feet above mean sea level.

According to a company pilot, the airplane had experienced 3 propeller strikes prior to the accident. The first occurred before the airplane was purchased by the company, the second occurred when the airplane was accidently taxied into a ditch, and the third occurred when the airplane was taxied over an area of uneven pavement at Lakefront Airport (NEW), New Orleans, Louisiana.

After the third propeller strike the airplane was out of service for approximately 4 months before it was repaired and placed back into service on February 28, 2011. The airplane’s most recent annual inspection was completed on March 24, 2011. At the time of the accident, the airplane had accrued 5696.3 total hours of operation.

METEOROLOGICAL INFORMATION

The reported weather at EYF at 1655, included: winds 190 degrees at 8 knots, 10 miles visibility, scattered clouds at 3,200 feet, scattered clouds at 3,800 feet, temperature 32 degrees C, dew point 23 degrees C, and an altimeter setting of 29.91 inches of mercury.

AIRPORT INFORMATION

Curtis L. Brown Field was uncontrolled and had one runway, 15/33. The runway was asphalt, and in good condition. The total length was 4,998 feet long and 75 feet wide. It was equipped with medium intensity runway edge lights and was marked with non-precision markings that were in good condition.

A 2-light precision approach path indicator was installed on the left side of runway 15. It displayed a 4.20 degree glide path.

Obstructions also existed on the approach path in the form of a 6 foot fence, 248 feet from the runway, 192 feet left of centerline, which required an 8:1 slope to clear.

WRECKAGE AND IMPACT INFORMATION

Post accident examination of the airplane by an FAA inspector revealed that the bottom of the airplane had come into contact with the runway pavement after the gear collapsed during the forced landing. Two of the four propeller blades exhibited curled tips, scrap marks, and areas where the propeller tips had holes worn through them. The nose gear tire was flat. The nose gear doors were bent, they exhibited scrape marks, and they were worn through in several areas. Several antennas mounted directly aft of the nose gear doors were also ground down. Further examination revealed that an approximate 12 by 24 inch area on the airplane's belly underneath the cabin entrance door, was also worn through to the pressure vessel structure, and the pressure vessel was substantially damaged.

Examination of the engine by the FAA also revealed no visible damage to the engine, no metal particles visible in the exhaust pipes, no visible fuel leaks, and no evidence of oil leaks. The engine was motored and the compressor turned over freely with no indication of compressor drag, blade rub, or bearing drag. Airflow and the smell of fuel was observed coming out of the exhaust pipes and turbine rotation was confirmed. Fuel was also observed to discharge from the combustion case drain and the start valve was confirmed to be closed.

TESTS AND RESEARCH

Engine Information

The PT6A-34 engine, installed in the airplane was a lightweight free turbine engine incorporating a reverse flow combustion path designed for aircraft propulsion use. It utilized two counter-rotating turbines; one driving the compressor and the other driving the propeller through a reduction gearbox. The latter turbine was “free” or independent of the compressor turbine.

It was modular in design and could be split into two major parts (the power section assembly and the gas generator assembly) for maintenance.

At the request of the NTSB the engine was removed from the airplane and shipped to PWC's St. Hubert, Quebec facility for further examination and testing.

Engine Examination

Examination of the engine, gear box housing, installed accessories, exhaust duct, and power turbine revealed no evidence of preimpact failures or malfunctions. The propeller shaft was intact and could be rotated freely by hand along with the power turbine rotor and the exposed accessory drives. The exhaust duct, and power turbine blades, also displayed no evidence of distress.

Examination of the gas generator case and accessory gearbox also revealed no evidence of any preimpact failures or malfunctions. The housing and installed accessories displayed no evidence of distress. The gas generator rotor turned freely, along with the accessory gearbox. The compressor 1st stage, compressor turbine guide vane ring, compressor turbine shroud, compressor turbine, accessory gearbox housing, and installed accessories also displayed no evidence of distress. Additionally, the accessory gearing rotated smoothly with the gas generator case rotor, along with all of the exposed accessory drives.

Examination of the fuel control unit manual override revealed the presence of an unapproved field modification. The fuel control unit manual override input lever was found to have been lockwired so that the travel was restricted from the stowed (idle) position to approximately 1/4 inch from the maximum (full rated power) stop set screw which would have rendered the engine unable to produce full rated power when using the manual fuel override. The input lever airframe input connection was also modified and was roughly countersunk from its as delivered configuration. The set screw lockwire lead seal, was in place and undisturbed.

Examination of the pneumatic lines also revealed anomalies. The compressor discharge air (P3) line was continuous from the gas generator case fitting to the fuel control input fitting however; the gas generator case fitting bolts were not lockwired. The power turbine control (Py) line propeller governor fitting lockwire was also found to be fractured at the loop through the “B” nut lockwire hole and the nut was found to be backed off approximately 1/3 to 1/2 turn, and the line could be moved by hand. Macroscopic inspection of the fracture showed features characteristic of overload fracture in tension and torsion at the location of a pre-existing nick. The fracture displayed no indications of fatigue or other progressive fracture mechanism. The forward fire seal fitting lockwire was also found to be overstressed and showed nicks where it looped through the “B” nut lockwire hole. The remaining lockwire and connections were intact.

Engine Functional Test

An engine functional test was conducted in a dynamometer test cell in accordance with PWC Overhaul Manual P/N 3021243 Section 72-00-00 “Engine Testing” procedures.

During the initial start, the gas generator speed (Ng) and fuel flow (Wf) stabilized at minimum fuel flow values. The engine however, displayed no response to power lever movement. The engine was then shut down and the Py line propeller governor “B” nut fitting was tightened. The engine was then restarted, and it accelerated normally to ground idle. All engine handling checks, acceleration to full power, feathering, bleed valve closing check, and manual override functional checks were normal.

To confirm fuel control bellows integrity the engine was then run at 34,000 RPM Ng for 10 minutes with negligible degradation of Ng RPM.

From idle power, the Py line propeller governor “B” nut fitting was then loosened to determine the point at which the Ng speed would fall to sub-idle. It was determined that loosening the fitting approximately 1/3 turn would bleed sufficient Py pressure for the Ng to fall to sub-idle.

Engine History

After the propeller strike that occurred at NEW, the engine was removed and disassembled and the power section and compressor sections were sent out for inspecti...