Stinson L 5 N45TX

Summary

On 14 June 2018 at about 22:00 local time, a Stinson L 5 registered N45TX was involved in an accident near Thomson, Georgia, 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

14 June 2018 at 22:00

Classification

Accident

Location

Thomson, Georgia, United States

Coordinates

33.6261, -82.4961

Aircraft

Stinson L 5

Registration

N45TX

Category

Airplane

Year built

1944

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Thomson → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA18LA168

Nobody was injured.

Failure of maintenance personnel to inspect the crankshaft after two previous propeller strikes, which resulted in failure of the crankshaft and a total loss of engine power. Contributing to the crankshaft failure was insufficient torque applied to the thrust nut.

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

Read the full NTSB narrative

While in cruise flight, the pilot noticed an increase in oil temperature and loss of oil pressure. Shortly thereafter, the engine lost total power, and the propeller stopped rotating. The pilot performed a forced landing to a lake, which resulted in substantial damage. Examination revealed that the propeller could not be rotated by hand, and the crankshaft was fractured at the No. 2 crank pin. Review of maintenance logbooks revealed that the most recent engine overhaul was performed about 24 years and 711 flight hours before the accident. Since that time, the propeller had been removed and replaced on two separate occasions due to propeller strikes. There was no record of any crankshaft inspections following either of the propeller strikes, contrary to manufacturer guidance. Additional damage found on the Nos. 1 and 2 cylinders was caused by the crankshaft failure and pistons that impacted their respective rods and skirts. In addition to the main fracture, a separate crack was discovered slightly aft of the No. 1 main bearing and had propagated nearly the width of the crankshaft, but had not fully failed. The thrust nut, which required 375 ft-lbs of torque, was easily removed without effort or special tools, indicating that it was torqued to a value significantly below specification. This could cause axial play along the crankshaft and contribute to the progression of the crankshaft failure that was likely initiated during the previous 2 propeller strikes. The crankshaft likely failed after its structural integrity was compromised during previous propeller strikes. The improper torque on the thrust nut likely exacerbated the failure of the crankshaft.

Quoted verbatim from the NTSB record.