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ASN Wikibase Occurrence # 141544
Last updated: 9 September 2021
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Type:Silhouette image of generic C172 model; specific model in this crash may look slightly different
Cessna 172P Skyhawk
Owner/operator:Civil Air Patrol, Inc.
Registration: N54872
MSN: 17275074
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Location:6th Street/East Davis Street, Conroe, TX -   United States of America
Phase: En route
Departure airport:Houston, TX (KIWS)
Destination airport:Conroe, TX (KCXO)
Investigating agency: NTSB
The airplane was at 1,600 feet mean sea level with the engine power set at 2,300 rpm. When the airplane was about 6 miles from the airport, the pilot heard a loud “boom” and the engine lost all power. The pilot did not have sufficient altitude to glide to the airport, so he landed the airplane on a street. When the airplane was on final approach to land, it collided with power lines. The pilot was able to land the airplane, but was forced to swerve to the right to avoid oncoming traffic. The right wing struck a utility pole, which resulted in substantial damage.

A postaccident engine examination revealed that when the crankshaft was turned, there was no movement of the intake or exhaust valves or magneto gears. The rear crank gear bolt was loose and the gear dowel pin was sheared, which would cause the camshaft and rear accessory gears to stop turning. Metallurgical examination revealed beach markings at the aft end of the crankshaft approximately in plane with the aft face of the crankshaft where it mated to the crankshaft gear. There was fretting damage on the crankshaft gear, wear on the dowel pins, and wear on the lock washer, indicative of movement as a result of insufficient clamping force from the attachment bolt at the time of installation. The engine had accrued 752 hours since it was overhauled in August 2007.
Probable Cause: Failure of the rear crankshaft gear dowel pin due to improper installation, which resulted in a total loss of engine power.



Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Duration: 3 months
Download report: Final report

Revision history:

04-Jan-2012 04:49 gerard57 Added
04-Jan-2012 05:46 gerard57 Updated [Aircraft type]
04-Jan-2012 05:46 PC 12 Updated [Aircraft type, Cn, Operator]
04-Jan-2012 15:10 Alpine Flight Updated [Time, Aircraft type, Operator, Location, Departure airport]
04-Jan-2012 22:53 RobertMB Updated [Source, Narrative]
13-Jan-2012 13:56 Dr. John Smith Updated [Time, Location, Destination airport, Source, Narrative]
13-Jan-2012 14:08 Dr. John Smith Updated [Location, Source, Narrative]
22-May-2012 22:26 Geno Updated [Location, Source, Narrative]
21-Dec-2016 19:26 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
27-Nov-2017 17:53 ASN Update Bot Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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