Winston W Walker THUNDER MUSTANG N244SW

Summary

On 24 October 2014 at about 15:00 local time, a Winston W Walker THUNDER MUSTANG registered N244SW was involved in an accident near Globe, Arizona, United States. One person was on board and one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

24 October 2014 at 15:00

Classification

Accident

Location

Globe, Arizona, United States

Coordinates

33.6203, -110.6999

Aircraft

Winston W Walker THUNDER MUSTANG

Registration

N244SW

Category

Airplane

Year built

2008

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Tucson → Tucson

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR15LA020

1 person was seriously injured.

The separation of the main crank drive pulley from the engine’s accessory section due to three of its securing bolts backing out of their holes, which subsequently resulted in two accessory belts becoming unsecure, both crank sensor plugs becoming dislodged, the ignition source to the engine being interrupted, and the total loss of engine losing total power.

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

Read the full NTSB narrative

The commercial pilot, who was also the owner/builder of the experimental, amateur-built airplane, reported that the purpose of the flight was to practice instrument approaches. He added that, after completing a practice instrument approach, executing the published missed approach procedure, and climbing to 6,500 ft mean sea level, he felt a reduction in power, followed by an rpm gauge reading of 0. The pilot subsequently made an off-field emergency landing to a dry river bed, which resulted in substantial damage to the airplane. A postaccident examination of the engine revealed that one of the three bolts that secures the main crank drive pulley to the associated damper was separated from the pulley and that the two bolts that remained in the pulley were loose. Additionally, both the left and right ignition leads were separated from their associated crank sensor plugs. Signatures on the main crank drive pulley's reluctor teeth were indicative of the main pulley having contacted the idler pulley and the idler arm subsequently separating from the pulley. This likely resulted in two accessory belts becoming unsecure, both crank sensor plugs becoming dislodged, and the subsequent total loss of engine power. A review of the maintenance records revealed that the engine had accumulated about 190 hours since its most recent overhaul. The pilot/owner stated that, when he reassembled the main crank drive pulley to the overhauled engine, he followed the procedures outlined in the engine's repair manual by torqueing each bolt to 35 ft-lbs of pressure and applying a thread-locking compound. However, visual and spectrographic analysis of material in the threads of the two recovered bolts did not detect signatures of the required thread-locking compound. Although this finding suggests that no thread-locking compound was used, it is not conclusive evidence that the compound was not applied during its most recent reassembly. Thus, the reason for the bolts becoming unsecured could not be conclusively determined.

Quoted verbatim from the NTSB record.