# NTSB NYC94IA023: Bell 206L, N16696, New York, NY, October 29, 1993 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: October 29, 1993, 12:40 local (16:40 UTC) - Place: New York, NY - Coordinates: 40.750263, -73.979446 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.7503&lon=-73.9794&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 6 uninjured - Status: Completed, report October 20, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 38692 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC94IA023 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/38692/pdf - Page: https://openairdocs.org/ntsb/NYC94IA023 ## Probable cause Inadequate maintenance which resulted in the improper alignment of the 'O' ring on the spur adapter gear drive which caused lack of lubrication and wear of the gear drive and the disengagement of the compressor and turbine. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, cruise - normal - turbine assembly,oil seal (contributing factor) - maintenance,alignment - inadequate, company maintenance personnel (cause) - Forced landing, descent - emergency - Ditching, landing - terrain condition - water ## Analysis THE HELICOPTER WAS ON A LOCAL SIGHTSEEING FLIGHT AND OVER THE EAST RIVER IN NEW YORK CITY WHEN THERE WAS A LOSS OF ENGINE POWER. THE PILOT DEPLOYED THE EMERGENCY FLOATS, INITIATED AN AUTOROTATION AND LANDED ON THE RIVER. EXAMINATION OF THE ENGINE FOUND AN 'O' RING WAS IN AN IMPROPER POSITION ON THE TURBINE SPLINED ADAPTER WHICH CONNECTS THE TURBINE AND COMPRESSOR SECTIONS OF THE ENGINE. IN ADDITION, THE SPLINED END WAS DRY OF LUBRICATION AND WORN TO THE POINT OF DISENGAGEMENT BETWEEN THE COMPRESSOR AND TURBINE. ACCORDING TO THE FAA, DURING ENGINE ASSEMBLY, THE 'O' RING IS INSTALLED AND CHECKED TO SEE THAT IT IS IN THE PROPER POSITION, THEN THE ENGINE HALVES ARE ASSEMBLED. DURING THE ASSEMBLY, WHEN THE 'O' RING IS NO LONGER VISIBLE IT COULD BE ROLLED OUT OF POSITION OR DAMAGED. THIS COULD PREVENT LUBRICATION FROM REACHING THE SPLINED END. ## Factual narrative On October 29, 1993, at 1240 eastern daylight time, a Bell 206L, N16696, owned and operated by Island Helicopters, Inc., of Garden City, New York, made a forced landing in the East River due to a power loss. There was no damage to the helicopter, and no injuries to the 2 pilots and 4 passengers. Visual meteorological conditions prevailed and no flight plan had been filed for the flight operating under 14 CFR Part 91. The helicopter was being operated on a local sighseeing revenue flight. It was cruising at 1400 feet. In the NTSB Accident Report, the pilot stated: ...At approximately 12:35 hours local we experienced an in flight engine shutdown. Ron was flying the aircraft and as soon as the failure occurred, I took the controls in a coordinated exchange. Ron had already started to initiate the autorotation. I armed the floats and issued a mayday call to LGA [La Guardia Control Tower]. Ron deployed the floats on my command and I completed the autorotation landing to water.... An engine tear down was conducted at Airwork, in Millville, New Jersey. It was observed by Mr. Mark Evans of Allison, Indianapolis, Indiana, and Mr. Bill Young, FAA, Farmingdale, New York. According to the engine records, it had been assembled by Island Helicopters. At the time of the power loss, the engine had accumulated 194.6 hours. According to a written report from Mr. Evans: Summary of Findings 1. The engine lost power due to loss of the splined joint at the turbine splined adapter and the aft end of the gas producer turbine to compressor coupling. The splines in this area were worn to the point of disengagement. 2. The splines in the area of distress appeared dry. 3. The "O" ring on the aft end of the spur adapter gearshaft was found cut and not in its proper position.... Additionally, Mr Evans said during the teardown, they found areas in the engine with carbon deposits that were consistent with a lack of lubrication. He also said the out of position "O" ring would cause a lack of lubrication to the splined adapter, and other areas of the engine. In a letter, Mr. Bill Young stated: ...There is an O-ring which is visually installed in the aft end of the compressor cavity. After which the installer should feel, with the tip of his finger, that the O-ring has seated properly...As the two halves of the engine are mated, the O-ring can no longer be seen. At this point, it could be rolled out of position or damaged. Should the above condition occur, a sufficient amount of oil to lubricate and cool the coupling might not be present to allow for proper operation of the coupling.... ## Aircraft - Registration: N16696 (not matched to a registry record) - Reported make and model: BELL 206L - Category: Helicopter - Serial number: 45101 - Airframe hours: 20432 - Engines: ALLISON 250-C20B 420 horsepower turbo shaft - Damage: No damage - Flight: Part 91 - Registered owner: Island Helicopters - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, October 19, 1993, 58 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 42; commercial; airplane ratings: multi-engine land; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 1,156 total, 16 in this make and model, 11 in the last 90 days, 11 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 9 knots - Visibility: 15 statute miles - Lowest ceiling: none - Temperature: 63 °F, dew point 36 °F - Altimeter: 29.00 inHg - Observed at: LGA, 7 nm away From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.