King LANCAIR 235/320 N717SK

Summary

On 12 December 1999 at about 23:50 local time, a King LANCAIR 235/320 registered N717SK was involved in an accident near Sterling City, Texas, 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

12 December 1999 at 23:50

Classification

Accident

Location

Sterling City, Texas, United States

Coordinates

31.8301, -100.9803

Aircraft

King LANCAIR 235/320

Registration

N717SK

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Kerrville → Big Spring

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

FTW00LA042

Nobody was injured.

The fatigue fracture of the propeller attaching bolts, due to improper torque during the installation of the propeller by other maintenance personnel. A factor was the lack of suitable terrain for the forced landing.

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

Read the full NTSB narrative

During descent, the propeller separated from the experimental airplane. The pilot initiated a forced landing to a county road, and during the approach, the left main landing gear 'struck the bottom wire of a two wire service line,' which crossed over the road. The airplane 'stalled,' yawed 20 degrees to the left, and 'hit the middle of the road on all three [landing] gear.' It then headed off the left shoulder of the road where the right wing hit a road sign, shearing off the outboard 4 feet of the wing. The propeller system was not recovered. Examination of four of the six propeller attaching bolts revealed that they failed as a result of fatigue. The shank of one of the bolts, in the area located immediately adjacent to the fracture face had been subjected to 'extensive rubbing damage.' Two of the submitted bolt pieces contained washers. Examination showed that both washers were permanently deformed into dish shapes and were galled by rubbing. Rubbing and galling damage was also found on contact surfaces of the self locking nuts on all four bolts. The 3-bladed wooden experimental propeller had 47.4 hours since installation. The combination of low time since installation and rubbing damage on the bolts indicates the application of inadequate pre-stress (low torque) during propeller installation.

Quoted verbatim from the NTSB record.