Piper PA-31-350 N555MC

Summary

On 14 September 2004 at about 23:15 local time, a Piper PA-31-350 registered N555MC was involved in an accident near Sweeny, Texas, United States. 2 people were 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

14 September 2004 at 23:15

Classification

Accident

Location

Sweeny, Texas, United States

Coordinates

28.9731, -95.8633

Aircraft

Piper PA-31-350

Registration

N555MC

Category

Airplane

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Port Lavaca → Houston

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

FTW04LA238

Nobody was injured.

The fracture failure of the left engine crankshaft for undetermined reasons.

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

Read the full NTSB narrative

The 1,800-hour commercial pilot reported that while in cruise flight, the left engine stopped producing power and the left propeller fell forward approximately six inches. The pilot secured the engine and made a precautionary landing. The airplane sustained substantial damage during the forced landing to a field. A review of aircraft maintenance records revealed that the airplane experienced a gear-up landing in January 2002, which resulted in a propeller strike. The left engine was removed and inspected per the manufacturer's overhaul manual and returned to service. The engine had accrued approximately 440 hours since it was overhauled. Examination of the engine revealed that the entire three-bladed propeller assembly and the #1 cylinder had separated from the engine. The engine was disassembled and the crankshaft, along with an intact #3 connecting rod assembly and the fractured #2 connecting rod assembly were examined by a Safety Board Materials Engineer. The crankshaft was fractured in two places; one fracture was just forward of the #3 rod journal in the crank cheek, and the other fracture was in the aft crank cheek adjacent to the #2 main journal. The interior surface of the #1 and #2 main bearing halves exhibited significant rubbing and a portion of the bearing liner material was delaminated and was missing from the forward end of the bearing. On the oil slinger face, just forward of the #1 main journal, 360 degree rubbing damage was noted just outboard of the radius. In the rub region, metallic transfer was present with a color consistent with aluminum material. No evidence of radial cracks was observed in this area. An exact determination for the crankshaft failure could not be determined; however, evidence supported two possibilities that could have attributed to its demise. One possibility was that the crankshaft fracture initiated from rubbing damage between the crank cheek aft of the #2 main journal (thrust face) and the crankcase, with the other fatigue region being secondary. The exact cause for the rubbing was not clear, but one possibility was that the bearing liner delaminated and liberated a section causing a reduction in the clearance between the crankshaft and the crankcase as it was rubbing/exiting through the oil slinger. The other possibility was that the propeller strike caused the rubbing/cracking to occur, which was not detected during the subsequent overhaul/inspection.

Quoted verbatim from the NTSB record.