Accident Hiller UH-12E N5360V,
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ASN Wikibase Occurrence # 133693
 
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Date:Tuesday 7 July 1998
Time:07:15 LT
Type:Silhouette image of generic UH12 model; specific model in this crash may look slightly different    
Hiller UH-12E
Owner/operator:Jack Gillette Flying Service
Registration: N5360V
MSN: 2113
Total airframe hrs:8600 hours
Engine model:Lycoming VO-540-C2A
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Destroyed
Category:Accident
Location:Eltopia, WA -   United States of America
Phase: Initial climb
Nature:Agricultural
Departure airport:
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot reported that he had just taken off to the south. About 30 seconds into the flight, a control paddle departed the helicopter, and control was lost. The helicopter crashed in a cornfield and rolled inverted, after which the pilot exited. Post-crash examination revealed that a flight control rotor blade departed the helicopter. The spar from the blade separated from a fatigue crack, which originated near one of the outboard retention bolt holes and propagated nearly all of the way around the spar on both sides. The NTSB materials laboratory determined that the fatigue cracking initiated from corrosion pitting. FAA Airworthiness Directives in effect at the time of the accident required inspection of the spar tube, cuff, and bolt holes every 100 hours to detect corrosion and cracking in accordance with a Hiller service bulletin. This service bulletin required a visual inspection for corrosion of the inside surface of the cuff and the inner and outer surfaces of the spar tube. This visual inspection was to be followed by a dye-penetrant inspection of the spar and the cuff to detect any cracks. Although logbook entries (of less than four months and 70 hours time in service before the accident) cited compliance with the relevant AD and service bulletin, no evidence was found of dye penetrant residue, zinc chromate primer, or the required sealant material during NTSB materials laboratory testing.

Probable Cause: Fatigue of the control rotor blade spar and failure of the maintenance inspector to follow the procedures set forth in the airworthiness directive.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: SEA98LA124
Status: Investigation completed
Duration: 1 year and 6 months
Download report: Final report

Sources:

NTSB SEA98LA124

Location

Revision history:

Date/timeContributorUpdates
21-Dec-2016 19:26 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
06-Apr-2024 19:29 ASN Update Bot Updated [Time, Other fatalities, Phase, Source, Narrative, Category, Accident report]

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