DEN07LA030

During takeoff, the pilot applied power to the engine, and the takeoff roll was smooth. The pilot noted that the runway centerline was somewhat obscured by snow and the airplane drifted slightly to the right of centerline. As the airplane accelerated to approximately 50 to 60 knots (1/3 down the runway), the airplane “suddenly turned hard to the left and started to skid,” according to the pilot. The pilot immediately reduced power to idle and did not apply brakes or reverse thrust. Subsequently, the airplane departed the left side of the runway. After repairs were completed from a previous incident, the accident airplane was equipped with a supplemental type certificate (STC) engine mount that eliminated the need for repetitive inspections required by the airframe manufacturer’s service bulletins (SBs). Following a number of cracked engine mounts and nose gear failures, several Piper SBs were issued and the original engine mount was redesigned. The redesign process included finite element model analysis and other testing programs. These design tools were not incorporated in the original mount design. During a postaccident examination of the original engine mount and the STC engine mount, investigators found that there was compliance (flexibility) in the engine mount actuator attach feet structure (in both versions), which sometimes resulted in cracks in the engine mount at the actuator feet. Although the STC version reduced the likelihood of fatigue cracking in the mount, compliance remained. The NTSB’s investigation determined that compliance could be exacerbated at some speeds, resulting in a high shimmying effect, and a subsequent uncommanded left or right turn of the nosewheel during takeoff or landing. The new engine mount, which the manufacturer subsequently replaced under warranty on all PA-46-500TP airplanes, incorporates a heavy-duty, one-piece design at the actuator attach point, eliminating the original two-piece design, which was produced in two-weld and one-weld versions. The new one-piece design provides a less compliant structure, which prevents relative motion between the two feet in the original engine mount design. Subsequent to this investigation, evidence was received of bulkhead damage immediately behind the engine mount found on a PA-46-310P. The accident airplane was reexamined in 2008, and similar firewall damage was found. The mechanical damage and marks were consistent with the engine mount contacting the bulkhead periodically before the accident.

History of flight

On November 30, 2006, at 0850 mountain standard time, a Piper PA-46-500TP, single-engine turboprop airplane, N804JH, sustained substantial damage when it impacted terrain following a loss of directional control during takeoff roll from the Steamboat Springs Airport/Bob Adams Field (SBS), Steamboat Springs, Colorado. The commercial pilot, who was the sole occupant, was not injured. The airplane was registered to Twin Landfill Corporation, Bozeman, Montana, and operated by the pilot. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the Title 14 Code of Federal Regulations Part 91 personal flight. The flight was originating at the time of the accident and was destined for Canon City, Colorado.

According to the pilot, during the taxi to runway 32, he noted the runway surface contained some icy and snow packed areas; however, the majority of the runway surface was exposed. The pilot stated that the partially snow covered runway was not a concern because he conducted operations with those conditions several times in the past. The pilot applied power to the engine and the takeoff roll was smooth. The pilot noted that the runway centerline was somewhat obscured by snow and the airplane drifted slightly to the right of centerline. Approximately 50 to 60 knots (1/3 of the way down the runway), the airplane "suddenly turned hard to the left and started to skid." The pilot immediately reduced power to idle and did not apply brakes or reverse. Subsequently, the airplane departed the left side of the runway. The airplane continued for approximately 300 feet in the snow-covered terrain before it came to rest. During the excursion, the nose gear collapsed and the propeller struck the terrain. The pilot reported the winds "a little above calm" at the time of the accident. The pilot stated that during previous takeoffs and landings, he felt “wobbling” from the nose gear. He added that he then tried to “keep the nose gear off the runway surface as long as possible” during takeoff and landing phases of flight.

Personnel information

The pilot, who was seated in the left front seat during the accident flight, held a commercial pilot certificate, with single-engine, multi-engine, and instrument airplane ratings. The pilot was issued a second-class medical certificate on December 28, 2005, with a limitation for corrective lenses. According to the Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1), the pilot reported he had accumulated a total of 3,160 flight hours, of which 207 hours were accumulated in the same make and model as the accident airplane. The pilot's most recent flight review was accomplished on September 6, 2006, in the accident airplane.

In the three months preceding the accident, the pilot had accumulated 55 hours in the accident airplane, of which 18 hours were dual instruction.

Aircraft information

The turboprop airplane, serial number 4697044, was manufactured in 2001 and issued a normal airworthiness certificate. At the time of the accident, the airplane had accumulated a total of 595 hours since new. The pilot purchased the airplane in January 2005.

The PA-46-500TP airplane is equipped with retractable tricycle air-oil strut type landing gear, which is hydraulically operated by an electric hydraulic pump. The landing gears swing to the down position and each actuator extends to its locked position, a switch located on each actuator activates to indicate by a green light that the gear is safely down and locked. Each landing gear is retracted and extended by a single hydraulic locking cylinder attached to the oleo strut housing. The gears are held in their up position by hydraulic pressure on the cylinder.

The nose gear is steerable through a 60-degree arc by use of the rudder pedals. Movement of the pedals is transmitted to the steering arm by two steering pushrods, a steering bellcrank and a steering bungee. As the gear retracts, 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 degree (left) to stow in the horizontal position.

The nose landing gear assembly (trunnion) attaches to the two forward lower attachment points on the engine mount. The nose gear downlock actuator attaches to the rear of the engine mount. The upper actuator fitting is secured in the rear engine mount attach feet with an AN 7-17 bolt, two washers and a locking nut.

On January 28, 2002, Piper issued Service Bulletin (SB) 1106, Nose Gear Steering System Improvement, which contained the following information. Purpose: There have been field reports of turning tendency immediately following nose wheel touch down during landings primarily, when cross wind conditions are present and/or when applying full propeller reverse. A contributing cause of the turning tendency has been identified as reduced nose gear steering authority, which under certain conditions, can allow the nose gear steering rotation to momentarily exceed the pilot's input. This Service Bulletin recommends mandatory incorporation of nose gear installation modifications that increase the pilot's steering authority. Failure to incorporate these modifications may increase the possibility of a turning tendency during landing. Compliance Time: To coincide with next regularly scheduled maintenance event, but not to exceed the next 100 hours time in service.

A review of the maintenance records revealed that SB 1106 was incorporated and installed on the accident airplane.

On November 25, 2003, Piper issued SB 1103B, Engine Mount Inspection, which contained the following information. Purpose: It has been determined that cracks may develop on the engine mount in the area of the nose gear actuator feet. This condition typically occurs when the nose landing gear is subjected to excessive loads, possibly through hard landings, rough field operations, excessive speed turns and/or improper towing of the aircraft. PART I of this SB requires a repetitive inspection of the engine mount. PART II of this SB requires replacement of the engine mount. Compliance Time: PART I Inspection to coincide with the next regularly scheduled maintenance event, and each 100 hours time in service or annual inspection, whichever occurs first, thereafter or until PART II of this SB is accomplished. PART II Replacement if cracks are found during the inspection in PART I, replace cracked engine mount. Note: Compliance with PART II of this SB will relieve the repetitive inspection requirements of PART I of this SB. PART II: Insure the new engine mount (P/N 102460-002) has the one piece feet. The old engine mount has a two piece welded foot. This welded area is where the cracks in the engine mounts have been found.

A review of the maintenance records revealed that SB 1103B Part I was completed on January 24, 2005, at a total airframe time of 433.0 hours. The records indicated the original engine mount was installed on the airplane.

During a January 2006 incident, the airplane sustained minor damage to the nose landing gear. According to the maintenance logbook entry for the repairs and information provided by the pilot, the engine mount was removed and shipped to Kosola & Associates, Inc., Albany, Georgia, for repairs (the type of repairs required were not specified in the records). During that time, the Kosola facility experienced a fire and the airplane's engine mount was destroyed.

While the airplane was undergoing repairs for the January 2006 incident, Piper issued SB 1154A, Engine Mount Inspection, on July 26, 2006, which contained the following information. Purpose: It has been determined that cracks may develop on the engine mount in the area of the nose gear actuator feet. This condition typically occurs when the nose landing gea