Piper PA-28-150 N991PK

Summary

On 12 November 1998 at about 20:00 local time, a Piper PA-28-150 registered N991PK was involved in an accident near Gila Bend, Arizona, 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

12 November 1998 at 20:00

Classification

Accident

Location

Gila Bend, Arizona, United States

Coordinates

32.9907, -112.9000

Aircraft

Piper PA-28-150

Registration

N991PK

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

San Diego → Phoenix

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX99LA029

Nobody was injured.

The crankshaft gear attach bolt loosening and backing out of its crankshaft bore, which led to the fatigue failure of the crankshaft gear dowel pin due to excessive working of the gear. The sequence of failures was the result of the engine overhaul shop's failure to comply with an Airworthiness Directive and the engine manufacturer's Service Bulletin.

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

Read the full NTSB narrative

The pilot said that no engine discrepancies were noted during either the preflight or the initial cruise portion of the flight, and that all engine instrument readings were normal. Between 500 and 1,100 mean sea level, the engine suffered a significant loss of power accompanied by sputtering, vibration, and the rpm fluctuating. He declared an emergency, performed the emergency checklist with no changes, and made a forced landing on a road. During the landing rollout the airplane struck a road sign that he had not seen. Postaccident inspection of the engine revealed the gear at the back of the crankshaft was detached and moving freely between the corresponding gears. The crankshaft gear attaching bolt and threads were undamaged and the bolt appeared to have backed out of the crankshaft and was resting in the crankshaft gear bore. The bolt locking plate remained at the head of the bolt, and exhibited fretting signatures. Fretting signatures were also located around the mating surfaces of the gear and crankshaft bore. The crankshaft gear dowel pin had failed, with fatigue striations visible to the naked eye. An engine overhaul was completed 1 month after an airworthiness directive (AD) was published requiring inspection of the crankshaft gear and the bolt to prevent the bolt from backing out and liberating the crankshaft gear. No evidence of compliance with this AD was found in the engine maintenance records.

Quoted verbatim from the NTSB record.