Kahului, HI, USA
N90Q
Eurocopter AS350D
During cruise flight the helicopter lost all engine power. The pilot made a hard forced during the autorotative descent onto a road. Post accident disassembly and examination of the engine disclosed that the power loss was due to the number two bearing sustaining significant damage [heavy roller deformation] and heat distress, consistent with an operating event with an insufficient oil supply. The engine had been leased by the operator from another firm. The operator's Director of Maintenance had installed the engine 13 operational hours prior to the accident flight. The record examination revealed, in part, that: (1) The engine’s serial number (S/N) data plate was defaced such that the S/N’s fifth numeric digit appears to have been overstruck onto the data plate, rendering the original, underlying digit illegible; (2) A 2003 logbook entry indicated that the engine was sold in an “as is” condition and was unserviceable, but the entry had a single line drawn through it with the word “void” and signed initials appearing above it; (3) a 2004 logbook entry indicated that long-term preservation was not accomplished, further maintenance was required, and a determination of serviceability was required before the next flight; and (4) the engine received an FAA Form 8130-3, “Airworthiness Approval Tag,” dated December 18, 2005, which certified that the engine was in “a condition for safe operation” and was found to be suitable for “return to service” per 14 CFR 43.9. The pilot stated that he did not observe illumination of any annunciator warning light on the helicopter's cockpit warning annunciator panel (CWP) prior to the power loss event. Illumination of CWP lights provides the pilot with an early indication of an impending problem. The brightness control switch on the CWP was found in the minimum brightness position, rather than in the maximum position recommended for daylight operation.
HISTORY OF FLIGHT On January 29, 2006, about 0907 Hawaiian standard time, a Eurocopter AS350D, N90Q, experienced a total loss of engine power during cruise flight. During the ensuing autorotative descent, the helicopter landed hard on a dirt road near Kahului, Maui, Hawaii, and it was substantially damaged. Neither the commercial certificated pilot nor six passengers were injured during the on-demand air tour sightseeing flight that was performed under the provisions of 14 CFR Part 135. The helicopter was operated by Alika Aviation, Inc., d.b.a. Alex Air. Visual meteorological conditions prevailed, and a company flight plan was filed. The flight originated from Kahului about 0900. The pilot reported to the National Transportation Safety Board investigator that after departure he climbed approximately 2,000 feet above ground level and commenced the planned 45-minute-long air taxi tour flight. En route, he heard a "couple of loud sounds" emanating from the engine and immediately thereafter, all engine power was lost. The pilot made a forced landing adjacent to a sugar cane field. The pilot stated that he performed a standard autorotation and landed the helicopter downslope on a dirt road and that, on final pitch pull, the tail stinger contacted the road, and the main rotor flexed into the tailboom. ENGINE AND MAINTENANCE RECORDS EXAMINATION The helicopter was recovered from the accident site. The operator's history of engine acquisition was examined. Also, selected airframe and engine components were examined along with associated maintenance records, including the rotorcraft's flight manual and the pilot's flight checklist. The helicopter's Daily Aircraft Maintenance Log indicated that on December 23, 2003, the helicopter had logged a total of 12,066 airframe cycles, and it had a total airframe time of 8,160.7 hours. Alex Air management reported to the Safety Board investigator that it had leased the accident engine (which was in storage) from Sunrise Helicopter, Inc., Spring, Texas, as a replacement for the engine that was in its helicopter. Upon delivery of the leased engine, Alex Air's Director of Maintenance installed the engine into the (accident) helicopter on December 30, 2005, inspected the helicopter, and determined that it was airworthy. The helicopter had not flown for about 2 years. Management at Sunrise Helicopter, Inc., reported that it had provided the airworthy (accident) engine to Alex Air along with associated logbook records documenting the engine's airworthiness. On January 29, 2006, at dispatch for the accident flight, the Daily Aircraft Maintenance Log indicated that the helicopter's total airframe time was 8,173.7 hours, and 12,090 cycles. Safety Board investigators and Rolls-Royce Allison Engine participants examined the leased (accident) engine and associated historical records. The Rolls-Royce engine investigation report (included in the docket for this accident) details the investigation findings and notes that "numerous discrepancies" were observed. The record examination revealed, in part, that: (1) The engine’s serial number (S/N) data plate was defaced such that the S/N’s fifth numeric digit appears to have been overstruck onto the data plate, rendering the original, underlying digit illegible; (2) A 2003 logbook entry indicated that the engine was sold in an “as is” condition and was unserviceable, but the entry had a single line drawn through it with the word “void” and signed initials appearing above it; (3) A 2004 logbook entry indicated that long-term preservation was not accomplished, further maintenance was required, and a determination of serviceability was required before the next flight; and (4) the engine received an FAA Form 8130-3, “Airworthiness Approval Tag,” dated December 18, 2005, which certified that the engine was in “a condition for safe operation” and was found to be suitable for “return to service” per 14 CFR 43.9. The following statement was made in the "Summary of Findings" section of the Rolls-Royce examination report: "The number two bearing exhibited significant damage [heavy roller deformation] and heat distress, consistent with an operating event of insufficient oil supply." MAGNETIC CHIP PLUG EXAMINATION During the examination of the helicopter, the Safety Board investigator, along with the operator's Director of Maintenance and the Federal Aviation Administration (FAA) coordinator, observed that the engine's lower accessory gearbox magnetic chip plug was covered with large chunks of broken magnetic metal. The electrical functionality to the engine chip (ENG.CHIP) detector was confirmed during the engine and accessory component examinations. CAUTION WARNING (ANNUNCIATOR) PANEL EXAMINATION The CWP's functionality was examined. Several of the light bulbs did not illuminate when the CWP was energized. A specific examination was performed of two annunciator lights related to engine operation. They are the engine chip (ENG.CHP) and the engine oil pressure (ENG. P) lights. The ENG.CHIP and ENG. P lights each contain two bulbs in their respective receptacles. The American Eurocopter participant reported that, based upon the findings related to the number two bearing failure, the first CWP light to illuminate in the accident scenario would likely be the ENG. P light. Subsequently, as the engine performance further deteriorated, the ENG.CHIP light should have illuminated, as metal deposits were found on the engine magnetic chip detector. (See the description of these and other CWP lights in the docket for this accident.) During the CWP's examination, the CWP was powered to check electrical continuity, and the individual light bulb filaments were visually examined. Both of the bulbs in the ENG.CHIP light illuminated. Neither of the bulbs in the ENG. P light illuminated. The two bulbs contained within the ENG. P. light were examined, and the filaments of both were observed broken with no apparent filament stretch. The CWP is equipped with a two-position toggle switch that controls the brightness of the bulbs. The switch positions are marked on the CWP, and they are "+" and "-" representing maximum and minimum brightness. HELICOPTER CHECKLIST AND VIDEOTAPE EXAMINATION According to Eurocopter's DGAC-approved "Flight Manual" checklist, the warning lamps (lights) are to be checked prior to flight. The accident pilot did not report observing illumination of any annunciator light prior to experiencing the total loss of engine power. The Safety Board's Video Laboratory, Washington, D.C., reviewed a videotape provided by a passenger on the accident flight. The video showed the CWP periodically during the last few minutes of flight. Specifically, views of the CWP were noted about 2 minutes 52 seconds, 2 minutes 39 seconds, and 2 minutes 19 seconds prior to ground impact. The autorotative descent commenced about 40 seconds prior to ground impact. At no time during the flight in which the CWP was visible were any of the bulbs in the CWP visibly illuminated. At all times during the flight when the CWP was visible, the toggle switch (brightness control) was observed in the "-" position, and the flight occurred during bright daylight conditions.
A total loss of engine power due to the internal effects on the bearings consistent with an operating event of insufficient oil supply. Contributing to the accident was the pilot’s improper flare during the autorotative descent.
Source: NTSB Aviation Accident Database
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