Maintenance Personnel’s Inadequate Maintenance Of The Magneto, Which Resulted In A Loss Of Engine Ignition

Location: Dallas, Texas Accident Number: CEN22LA344
Date & Time: July 28, 2022, 14:38 Local Registration: N3027J
Aircraft: Piper PA-32RT-300T Aircraft Damage: Substantial
Defining Event: Powerplant sys/comp malf/fail Injuries: 1 Serious
Flight Conducted Under: Part 91: General aviation – Personal

Analysis: The pilot declared an emergency to air traffic control after the airplane’s engine began to run rough while en route to the destination airport. He received radar vectors to an alternate airport but was unable to reach that airport. During the subsequent off-airport landing, the airplane impacted trees and sustained substantial damage to the wings and fuselage. Postaccident examination of the airplane revealed the magneto case’s cover screws were loose and there was corrosion present on the magneto housing. The corrosion would have resulted in the magneto’s capacitors not properly grounding to the magneto case due to the corrosion, which also resulted in electrical arcing near the points and melting that was found on the cam follower. Without a proper attachment of the magneto case due to the loose cover screws, there would have been a slight case separation that would result in a simultaneous failure of both magneto sides due to a lack of ground.

A review of airframe logbooks showed that there was no logbook entry, as required by regulation, stating that the magneto was removed and replaced after a 500-hour inspection of the magneto was performed by a repair station. An invoice from a maintenance facility to the pilot stated that the magneto was removed and replaced for a 500-hour inspection. The repair station’s Airworthiness Approval Tag for the magneto stated that the installer of the magneto must comply with the magneto manufacturer’s Service Bulletin SB651, which was not performed based on the corrosion and electrical arching found during the postaccident examination.

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be — Maintenance personnel’s inadequate maintenance of the magneto, which resulted in a loss of engine ignition, a loss of engine power, and a subsequent forced landing.

FMI: www.ntsb.gov