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ASN Wikibase Occurrence # 148726
Last updated: 26 November 2021
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Date:01-SEP-2012
Time:11:30
Type:Silhouette image of generic TL20 model; specific model in this crash may look slightly different
TL Ultralight TL-2000 StingSport
Owner/operator:Sting4fun Llc
Registration: N898N
MSN: TLUSA129
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Substantial
Category:Accident
Location:Between Mead, and Longmont, CO -   United States of America
Phase: En route
Nature:Private
Departure airport:Erie, CO (EIK)
Destination airport:Erie, CO (EIK)
Investigating agency: NTSB
Narrative:
While conducting maneuvers at 2,500 feet, the airplane began to vibrate violently. The pilot aborted the maneuver and retarded the throttle to idle; the engine experienced a total loss of power. The pilot executed a forced landing into a field. After the landing, the pilot and the designated pilot examiner noticed that two of the propeller blades had separated from the propeller hub. An examination of the fractured blades and blade sleeves revealed that blade A likely fractured due to progressive cracking at laminate bonds at the interface between the wood blade and the metal sleeve. The powdery wood observed in the slots and at the root end of the blade shank were indicative of rubbing wood as the cracks progressed. The blade B fracture was likely secondary and occurred due to the vibrations associated with the imbalance created by the blade A fracture and subsequent separation. The propeller log indicated that manufacturer-specified visual inspections and torque checks were not conducted at the specified interval of 150 hours but at intervals of about 203, 320, and 250 hours. The delayed visual inspections reduced the likelihood of detecting the cracks and the delayed torque checks might have contributed to crack growth in the blade.

Probable Cause: The failure of the wood propeller blades in flight. Contributing to the accident was the owner/operatorís failure to complete required inspections on the propeller within the specified interval, which reduced the likelihood of detecting the cracks and may have contributed to the crack growth.

Sources:

NTSB

Accident investigation:
cover
  
Investigating agency: NTSB
Status: Investigation completed
Duration: 1 year and 7 months
Download report: Final report
Location


Revision history:

Date/timeContributorUpdates
05-Sep-2012 22:23 Geno Added
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
28-Nov-2017 13:26 ASN Update Bot Updated [Operator, Nature, Departure airport, Destination airport, Source, Narrative]

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