Piper PA-25-235 N86AB

Summary

On 18 March 2013 at about 19:05 local time, a Piper PA-25-235 registered N86AB, operated by Aerial Banners Inc, was involved in an accident near Panama City, Florida, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

18 March 2013 at 19:05

Classification

Accident

Location

Panama City, Florida, United States

Coordinates

30.3414, -85.8319

Aircraft

Piper PA-25-235

Registration

N86AB

Category

Airplane

Year built

1965

Engines

1

Operator

Aerial Banners Inc

Operating rule

Part 91: General Aviation

Purpose of flight

Banner Tow

Phase of flight

Not recorded

Route

Panama City → Panama City

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA13LA174

1 person had minor injuries.

A loss of preload to the crankshaft gear attachment bolt, resulting in rotation of the crankshaft gear and a subsequent total loss of engine power. The root cause for the loss of preload could not be determined during a postaccident examination of the components.

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

Read the full NTSB narrative

The pilot departed and picked up an aerial advertising banner for a local flight. About 6 minutes later, the airplane's engine suddenly lost all power. The pilot unsuccessfully attempted to troubleshoot the loss of engine power, jettisoned the banner at an altitude of about 500 feet, and performed a forced landing to a pine forest below, which resulted in substantial damage to the airplane. Postaccident examination of the engine revealed that the crankshaft gear alignment dowel had sheared and that the gear had rotated from its normal position. The gear's attaching hardware remained installed and undamaged. Detailed examination of the gear and alignment dowel showed that their hardness was consistent with that required by the design and that they were within or nearly within nominal dimensional tolerances described by the manufacturer. The counter-bored pilot hole at the aft of the crankshaft where the gear was seated was between 0.0008 and 0.0013-inch oversized. There were no discrepancies found with the retaining bolt, and it could be threaded into the crankshaft with minimal resistance. A definitive cause for the loss of preload to the crankshaft gear attaching bolt could not be determined during the engine examination. Review of maintenance records showed that the engine had been installed onto the accident airplane following an overhaul, which was originally precipitated by a propeller strike. The records provided that documented the overhaul and returned the airplane/engine to service lacked language specifying compliance with a manufacturer service bulletin that provided explicit instructions for the installation of the crankshaft gear to the crankshaft; however, the provided records did document part numbers and torque values consistent with those specified by the service bulletin.

Quoted verbatim from the NTSB record.