Piper PA 30 N8244Y

Summary

On 5 June 2020 at about 01:21 local time, a Piper PA 30 registered N8244Y was involved in an accident near Salem, Oregon, 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

5 June 2020 at 01:21

Classification

Accident

Location

Salem, Oregon, United States

Nearest airport

McNary Fld (SLE)

Coordinates

44.9094, -123.0025

Aircraft

Piper PA 30

Registration

N8244Y

Category

Airplane

Year built

1965

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Medford → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR20LA252

Nobody was injured.

A fatigue failure of the right main landing gear trunnion.

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

Read the full NTSB narrative

The pilot reported that, after departure, he raised the landing gear and heard an unusual "clunk"; however, he did not observe any anomalies at the time and continued the flight. As the airplane neared the destination airport, the pilot extended the landing gear, but the landing gear did not fully extend. After troubleshooting, including attempting the emergency extension procedure, the pilot landed the airplane with the gear partially extended, during which the airplane sustained substantial damage to the keel beam and the right-wing spar. Postaccident examination revealed that the right main landing gear trunnion was fractured as the result of two fatigue cracks that had developed at a welded gusset joined to a protruding boss. Once these fatigue cracks had propagated far enough into the boss cross-section, the remainder of the part fractured by overstress, likely during the last landing. The presence of two opposite-facing fatigue cracks was consistent with reverse bending fatigue. The fatigue cracks initiated at a tapered neck-shaped area, where the gusset and trunnion were joined. The cross-sectional thickness at this location was half the thickness of the gusset and a quarter of the diameter of the boss. This configuration would introduce a stress concentration at the locations of the fatigue cracking. The trunnion boss was consistent with a heat-treated aluminum alloy. The hardness approaching the welded joint decreased, consistent with softening from the heat input. The reduced hardness would increase susceptibility to fatigue crack initiation at the areas of stress concentration. It is likely that, over time, the fatigue cracks propagated as the joint flexed or bent back and forth, and the stress concentrations at the neck-shaped region were exacerbated by the reduced mechanical properties of that region. The fracture surfaces were damaged after the accident, and, due to the amount of post-fracture damage, no reliable fatigue analysis could be performed.

Quoted verbatim from the NTSB record.