On April 18, 1994, a Hughes 369D (registration N1103N) operated by Pacific Aviation International was involved in an aviation accident near Hanapepe, HI. Investigators recorded the probable cause as: INADEQUATE TURBINE ENGINE COMPRESSOR CLEANING PROCEDURES BASED ON INFORMATION IN THE MANUFACTURER'S SERVICE LETTER, AND LOSS OF ENGINE POWER DUE TO BLOCKAGE OF THE FUEL NOZZLE STRAINER WITH FOREIGN MATERIAL (SODIUM). This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A Hughes 369D helicopter lost engine power while maneuvering near a waterfall on a sightseeing flight, subsequently landing hard on rough terrain. Examination revealed the fuel nozzle strainer was contaminated and blocked with sodium, with flow rates below manufacturer specifications.
Incident Description
During a sightseeing flight, a Hughes 369D helicopter was maneuvering near a waterfall when it experienced a loss of engine power. The helicopter descended and landed hard on rough, rocky terrain.
Examination Findings
An examination of the engine revealed that the fuel nozzle strainer was contaminated and blocked with sodium. The strainer was also partially collapsed. Tests of the nozzle showed that fuel flow rates were below the manufacturer's specifications.
Maintenance Context
The helicopter was operated exclusively in a marine environment. The operator performed compressor wash procedures on a daily basis. A service letter from the engine manufacturer prescribed turbine engine compressor wash procedures that resulted in the immersion of the fuel nozzle in contaminated wash water. There was evidence of subsequent infiltration of wash water into the fuel nozzle strainer. The fuel nozzle strainer had a life limit of 2,500 hours, but according to the manufacturer, it was not subject to any prior routine inspection requirement.
Frequently asked questions
What happened in the 18 Apr 1994 Hughes 369D accident near Hanapepe, HI?
A Hughes 369D helicopter lost engine power while maneuvering near a waterfall on a sightseeing flight, subsequently landing hard on rough terrain. Examination revealed the fuel nozzle strainer was contaminated and blocked with sodium, with flow rates below manufacturer specifications.
What aircraft was involved and where did it happen?
The accident on 18 Apr 1994 involved a Hughes 369D, registration N1103N, operated by Pacific Aviation International, at Hanapepe, HI.
What was the probable cause of the accident?
INADEQUATE TURBINE ENGINE COMPRESSOR CLEANING PROCEDURES BASED ON INFORMATION IN THE MANUFACTURER'S SERVICE LETTER, AND LOSS OF ENGINE POWER DUE TO BLOCKAGE OF THE FUEL NOZZLE STRAINER WITH FOREIGN MATERIAL (SODIUM). FACTORS RELATED TO THE ACCIDENT WERE: THE LACK OF A SPECIFIED SERVICE REQUIRMENT FOR INSPECTION OF…
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