Accident Hiller UH-12E N3004T,
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ASN Wikibase Occurrence # 297374
 
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Date:Monday 22 April 2002
Time:10:30 LT
Type:Silhouette image of generic UH12 model; specific model in this crash may look slightly different    
Hiller UH-12E
Owner/operator:Sundance Helicopters, Inc.
Registration: N3004T
MSN: 5012
Total airframe hrs:4114 hours
Engine model:Lycoming VO-540-C2A
Fatalities:Fatalities: 0 / Occupants: 3
Aircraft damage: Substantial
Category:Accident
Location:Goshen, Oregon -   United States of America
Phase: Unknown
Nature:Survey
Departure airport:Eugene Airport, OR (EUG/KEUG)
Destination airport:Creswell, OR (77S)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
While in cruise flight the engine experienced a total loss of power in the Hiller UH-12E rotorcraft. In an attempt to avoid a water landing he maneuvered over trees and then ran out of rotor RPM landing hard. Post crash examination revealed that the left hand exhaust stack tube inside the cylindrical stainless steel heat muffler was cracked and separated circumferentially in the vicinity of an old weld. The left side muffler was dedicated exclusively to providing engine heated air for carburetor heat application. The exhaust stack tube was observed to be thin and heat distorted and the circumferential split was noted to be in the vicinity of an old weld. The split in the tube allowed hot engine exhaust to duct directly to the carburetor via the carburetor heat plenum. Additionally, the carburetor heat valve within the plenum to the carburetor was found to be out of rig such that when carburetor heat was fully de-selected in the cockpit (FULL COLD), engine heated air was still partially flowing to the carburetor intake. A 100-hour inspection had been completed and signed off by company maintenance personnel 19.8 hours previous to the accident. Appendix D to Part 43 of the Federal Aviation Regulations requires each person performing an annual or 100-hours inspection to inspect (where applicable) components of the engine and nacelle group including exhaust stacks - for cracks, defects, and improper attachment.

Probable Cause: The failure of company maintenance personnel to identify and replace/repair the degraded exhaust stack. Contributing factors were the mis-rigged carburetor heat control and the pilot's failure to maintain appropriate rotor RPM. Additional contributing factors were trees and water.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: SEA02LA073
Status: Investigation completed
Duration: 1 year
Download report: Final report

Sources:

NTSB SEA02LA073

Revision history:

Date/timeContributorUpdates
14-Oct-2022 17:50 ASN Update Bot Added

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