CEN09IA153

The pilot's inability to maintain directional control of the airplane during landing for undetermined reasons.

The private pilot and passenger were landing following a cross-country flight. As soon as the nosewheel touched down on landing, the airplane pulled to the left. The pilot attempted to correct to the right and the airplane began swerving and exited the right side of the runway and came to a stop in a snow bank. The pilot told investigators the airplane had seven previous instances of the airplane pulling to the left during landing. In each of those cases, the steering departure occurred upon nosewheel touchdown and the pilot was able to regain control. Weather at the time of the accident was clear skies and the winds were variable at five knots. Postaccident examination of the airplane showed the nose gear rake angle was negative (-) .5 to -.7 degrees. Proper rake angle is 0.0 to positive .5 degrees. The manufacturers's analysis of the measured -.5 to -.7 degree rake angle showed that the rake angle maintained a positive margin of safety against dynamic nosewheel shimmy. The investigation could not determine the cause of the steering departure.

HISTORY OF FLIGHT On February 4, 2009, about 1230 mountain standard time, a Piper PA-46-500TP airplane, N535JR, departed the runway during landing at the Aspen-Pitkin County Airport (ASE), Aspen, Colorado. Visual meteorological conditions prevailed at the time of the incident. The airplane received minor damage, and neither the private pilot or passenger were injured. The cross- country flight was being operated as a personal flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91, and an instrument flight rules (IFR) flight plan was filed. The flight originated at Richard Lloyd Jones Airport (RVS), Tulsa, Oklahoma, and was terminating at the time of the incident. The pilot stated that he made a smooth landing on the main wheels and as soon as the nose wheel touched down the airplane began veering left and right uncontrollably. The airplane exited the right side of Runway 15 about 2,000 feet down the runway and came to rest in a snow bank. The pilot also reported this airplane had seven previous events of the airplane pulling to the left during landing. In each of those cases, the steering departure occurred upon nose wheel touchdown and the pilot was able to regain control. There were no reports to the NTSB or FAA for any of the prior events. PERSONNEL INFORMATION The pilot, age 50, held a private pilot certificate with airplane single engine land and instrument ratings. His last flight review occurred on November 3, 2008. His last third class medical evaluation occurred on June 1, 2007. According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1), he had 1,600 total flight hours and 500 flight hours in this make and model of airplane at the time of the accident. AIRCRAFT INFORMATION The six-seat, low wing, retractable gear airplane, serial number (S/N) 4697253, was manufactured in 2006. It was powered by a Pratt and Whitney Canada PT6A-42A 500 horsepower engine and equipped with a Hartzell HC-E4N-3Q propeller. A review of the maintenance logbook records showed an annual inspection was completed September 9, 2008, at a recorded 527.8 hours airframe total time and tachometer time. The airplane had accumulated 680 hours total time and tachometer time at the time of the incident. This model airplane is equipped with a retractable tricycle air-oil strut type landing gear which is hydraulically operated by an electric hydraulic pump. A selector handle or switch on the instrument panel to the left of the control quadrant is used to select gear UP or DOWN positions. The nose gear is steerable through a 60 degree arc by use of the rudder pedals. As the gear retract, the steering linkage becomes separated from the gear so that rudder pedal action with the gear retracted is not impeded by the nose gear operation. The nose gear rotates 90° to stow in the horizontal position. A steering bungee is also incorporated in the nose wheel steering mechanism. METEORLOGICAL INFORMATION Weather at ASE at 1153 was reported clear skies, temperature 33 degrees Fahrenheit, altimeter 30.43, and winds calm. The pilot and airport personnel reported variable winds at 5 knots at the time of the accident. AERODROME INFORMATION Runway 15 at ASE is 7,006 feet by 100 feet at an elevation of 7,679.8 feet mean sea level (MSL). It has a grooved asphalt surface and a 2.0 percent up-sloping gradient. TESTS AND RESEARCH The landing gear and nose wheel steering systems were examined for anomalies and proper operation by investigators. With weight on wheels, the nose gear strut extension measured 2.212 inches, the right main landing gear (MLG) strut extension measured 2.75 inches, and the left MLG strut extension measured 2.8125 inches. The nose wheel tire pressure was 70 pounds per square inch (psi). The steering rake angle measured between -.5 degrees and -.7 degrees. The nose wheel strut had .2 degrees of fore/aft movement, which accounted for the differences in the measured rake angle. Piper Aircraft, Inc. PA-46-500TP, Malibu-Meridian Maintenance Manual, Figure 4 (Nose Gear Adjustment), page 4G8, depicted the proper steering rake angle as 0.0 degrees to +0.5 degrees. Nose wheel steering roller clearance was measured with weight-on-wheels and on jacks (weight-off- wheels). With weight-off-wheels, the left and right steering roller clearances both measured greater than .035 inches. With weight-on-wheels, the left and right steering roller clearances both measured .020 inches. The recommended clearance is 0.010 - 0.030 inches with weight on wheels. Rudder cable tension was examined and was found to be appropriately set. The pilot stated at the time of the event landing both passengers weighed 285 pounds, there was 560 pounds of fuel, and 75 pounds of cargo in the rear cargo area. This information was provided to engineers at Piper Aircraft to compute the margin of safety with these conditions and with a nose wheel rake of -.5 to -.7 degrees. According to Piper engineers, “based on this incidents inputs and a 78 knot indicated landing speed (ref. P.O.H. section 5 landing ground roll maximum touchdown speed), shimmy analysis shows a positive margin of safety against dynamic shimmy ( MS = +.14) , even with a negative .70 degree rake angle.” The airplane engine mount, part number 102460-036, S/N 116192, was installed at the Piper Aircraft manufacturing facility and was original manufacturer equipment. Post incident, the engine mount was removed from the airplane and examined at the Piper Aircraft, Inc. manufacturing facility. Prior to removal, there was no evidence of contact between the engine mount and the engine firewall. The nose gear actuator attachment bolt and nut were also intact and turned freely in the actuator mounting hole. The engine mount, which was white in color, was inspected visually and by non-destructive inspection (NDI) methods. No evidence of flexing, cracking, or impact damage was found. The mount was placed in a straightening jig to determine if any bending or misalignment were present. The mount did not show any signs of bending or misalignment. ADDITIONAL INFORMATION Piper Aircraft provided historical information on takeoff and landing excursions of PA-46-500TP airplanes. That data indicated twenty events of runway excursions, in addition to this incident. Six of the events were investigated by the NTSB. Of those six events, four (CHI07IA067, DEN07LA030, MIA07LA038, SEA07IA058) were attributed to deficiencies or failures of the engine mount, one (DEN05LA109) to pilot error, and one (LAX05LA116) to undetermined reasons. The remaining fourteen events were not investigated by the Safety Board since substantial damage and/or serious injuries were not involved. Therefore, limited data was obtained regarding those events. This event was the second recorded runway departure in an airplane equipped with the newest, third generation engine mount (part number 102460-036). The first occurrence occurred on February 27, 2008, with airplane S/N 4697148. This incident resulted in minor damage. The cause of the incident was undetermined. Written Guidance - PIPER AIRCRAFT, INC., PA-46-500TP, MALIBU MERIDIAN MAINTENANCE MANUAL (PA-46 MM), April 15, 2007, contained the following information under the Troubleshooting Nose Gear section: Nose Gear fails to straighten when landing gear extends. - Steering arm roller sheared at top of strut. o Replace defective roller. - Incorrect rigging of nose gear steering. o Check nose gear steering adjustment. On page 4G6 of PA-46 MM, Nose Gear Assembly, Installation, Step B. (5) said “Check the alignment of the nose gear assembly – Alignment, below.” Following the installation checklist were two figures, one labeled “Nose Gear Installation – Figure 3” on page 4G7 and one labeled “Nose Gear Adjustment - Figure 4” on page 4G8. Figure 4 was a diagram of the nose gear