NTSB Identification: SEA02LA073.
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Accident occurred Monday, April 22, 2002 in Goshen, OR
Probable Cause Approval Date: 04/23/2003
Aircraft: Hiller UH-12E, registration: N3004T
Injuries: 3 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

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.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

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.

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