Piper PA-46-500TP N804JH

Summary

On 30 November 2006 at about 15:50 local time, a Piper PA-46-500TP registered N804JH was involved in an accident near Steamboat Springs, Colorado, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

30 November 2006 at 15:50

Classification

Accident

Location

Steamboat Springs, Colorado, United States

Nearest airport

Steamboat Springs/Bob Adams Fi (SBS)

Coordinates

40.5161, -106.8661

Aircraft

Piper PA-46-500TP

Registration

N804JH

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Steamboat Sprin → Canon City

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

DEN07LA030

Nobody was injured.

The inadequate design of the engine mount, which caused an uncommanded left turn, loss of directional control, and impact with snow-covered terrain. Contributing to the accident was the low nose gear tire pressure.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.