SACRAMENTO, CA, USA
N114FD
Bell UH-1H
The helicopter landed hard following a loss of engine power in the traffic pattern. The pilot reported that he picked up the helicopter after maintenance was performed on the audio and visual low rpm warning systems and was positioning the helicopter to back to the airport. As he entered the pattern, he heard a bang and what he described as "a horribly loud grinding sound coming from the rear of the aircraft," and lost engine power. The pilot entered an autorotation to a clear area on the airport. As the helicopter neared the touchdown point, the pilot realized the selected landing area was sloped and so he increased collective to extend the glide to reach a flat area. The helicopter landed hard. A teardown and examination of the engine disclosed that the type and degree of damage to the engine was indicative of the separation of a portion of a planetary reduction gear, which resulted in a piece of inlet housing entering the compressor. This resulted in damage to the compressor airfoils and a loss of power. The separation of the portion of planetary reduction gear was determined to be the result of a fatigue fracture emanating from the aft root corner of one gear tooth. The root cause of the fatigue fracture could not be determined due to smearing of the initiation site. The planetary gears installed in the engine were military direct purchase breakout parts. The engine manufacturer does not approve of the use of military direct purchase hardware in FAA certified or military surplus engines used in public-use operations.
On October 15, 2003, at 1327 Pacific daylight time, a Bell UH-1H, N114FD, experienced an in-flight engine fire and made an emergency landing at Mather Field, Sacramento, California. The Sacramento Metro Fire Department was operating the helicopter under the provisions of 14 CFR Part 91. The commercial pilot, the sole occupant, was not injured; the helicopter sustained substantial damage. The public-use positioning flight departed Rancho Murietta, California, about 1320, en route to McClellan Airport, Sacramento. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported that he picked up the helicopter after maintenance was performed on the audio and visual low rpm warning systems and he was positioning the helicopter to McClellan. As he flew near Mather, he heard a bang and what he described as "a horribly loud grinding sound coming from the rear of the aircraft," and lost engine power. The pilot entered an autorotation to a clear area on the airport. As the helicopter neared the touchdown point, the pilot realized the selected landing area was sloped and so he increased collective to extend the glide to reach a flat area. The helicopter landed hard. The engine was removed from the aircraft and shipped to the Honeywell Product Integrity Investigation Laboratory, Phoenix, Arizona, where a teardown inspection was conducted under the supervision of a National Transportation Safety Board investigator. The complete report of the teardown and subsequent materials laboratory analysis is contained in the public docket for this accident. According to the Honeywell report, in summary, the teardown and examination of the engine disclosed that the type and degree of damage to the engine was indicative of the separation of a portion of a planetary reduction gear, which resulted in a piece of inlet housing entering the compressor. This resulted in damage to the compressor airfoils and a loss of power. The separation of the portion of planetary reduction gear was determined to be the result of a fatigue fracture emanating from the aft root corner of one gear tooth. The root cause of the fatigue fracture could not be determined due to smearing of the initiation site. The planetary gears installed in the engine, including the separated gear, were identified with CAGE code 81996, indicating that the parts were military direct purchase breakout parts. Honeywell does not approve of the use of military direct purchase hardware in FAA certified or military surplus engines used in public-use operations.
The loss of engine power due to the fatigue failure of a planetary reduction gear.
Source: NTSB Aviation Accident Database
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