ASN Wikibase Occurrence # 157414
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Date: | Sunday 12 December 1999 |
Time: | 17:50 |
Type: | Lancair 235/320 |
Owner/operator: | Private |
Registration: | N717SK |
MSN: | 069 |
Total airframe hrs: | 721 hours |
Fatalities: | Fatalities: 0 / Occupants: 1 |
Aircraft damage: | Substantial |
Category: | Accident |
Location: | Near Sterling City, TX -
United States of America
|
Phase: | En route |
Nature: | Private |
Departure airport: | Kerrville, TX (ERV) |
Destination airport: | Big Spring, TX (T49) |
Investigating agency: | NTSB |
Confidence Rating: | Accident investigation report completed and information captured |
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.
Probable Cause: 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.
Sources:
NTSB:
https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001212X20239&key=1 Revision history:
Date/time | Contributor | Updates |
02-Jul-2013 09:49 |
JINX |
Added |
02-Jul-2013 13:49 |
harro |
Updated [Aircraft type, Operator] |
21-Dec-2016 19:28 |
ASN Update Bot |
Updated [Time, Damage, Category, Investigating agency] |
14-Dec-2017 10:01 |
ASN Update Bot |
Updated [Source, Narrative] |
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