# NTSB FTW01LA036: Bell 206B, N222LM, Rockport, TX, December 1, 2000 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 1, 2000, 16:19 local (22:19 UTC) - Place: Rockport, TX - Location: 28.0478° N, 97.0499° W: Placed by OpenAirDocs: center of Rockport, TX, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=28.0478&lon=-97.0499&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report October 9, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 51160 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW01LA036 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/51160/pdf - Page: https://openairdocs.org/ntsb/FTW01LA036 ## Probable cause the loss of engine power during cruise flight due to the fatigue fracture of the compressor coupling adapter. A contributing factor was the high sea condition existing for the forced landing. ## 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 - turboshaft engine,gas generator turbine shaft - fatigue (cause) - turboshaft engine,gas generator turbine shaft - failure (cause) - Forced landing, descent - emergency - autorotation - performed, pilot in command - In flight collision with terrain/water, landing - flare/touchdown - terrain condition - large wave/swell (contributing factor) - rotor system,tail rotor - blade strike ## Analysis The helicopter was returning to shore from an oil platform. The pilot had just made a "5 mile advisory call" announcing his intention to land at his destination when the engine chip light illuminated; this was followed by an immediate loss of engine power. The pilot initiated an autorotation, inflated the floats and made a mayday call. During the descent, he "had full [aircraft] control to include tail rotor authority." During landing, the tail rotor blades entered the water resulting in sudden stoppage of the tail rotor, which twisted the tail rotor drive shaft apart. Following the landing, the helicopter remained upright, and the pilot exited the helicopter after the main rotor blades came to a stop due to the "waves and wind." After he moved away from the helicopter, it rolled over. The pilot reported that the wind was from 045 degrees at 15 knots gusting to 25 knots. An examination of the turbine engine revealed that the N1 gas producer would not turn. Disassembly of the engine revealed that the compressor coupling adapter was fractured. Metallurgical examination indicated that the compressor coupling adapter had failed due to fatigue initiating from fretting at the outer surface where it contacted the impeller. The source of the fretting could not be determined. ## Factual narrative On December 1, 2000, at 1619 central standard time, a Bell 206B helicopter, N222LM, was substantially damaged during a water landing following a loss of engine power near Rockport, Texas. The helicopter was owned and operated by American Helicopters, Inc., of Galveston, Texas. The commercial pilot, sole occupant, was not injured. Visual meteorological conditions prevailed, and a company VFR flight plan was filed for the 14 Code of Federal Regulations Part 91 positioning flight. The flight originated from the Matagorda 603 offshore platform located in the Gulf of Mexico, at 1555, and was destined for the Aransas County Airport, Rockport, Texas. The pilot reported that he had just made a "5 mile advisory call" announcing his intention to land at the Aransas County Airport when the engine chip light illuminated; this was followed by an immediate loss of engine power. The pilot initiated an autorotation, inflated the floats and made a mayday call with direction, distance from the airport, and the cause of the mayday call. During the descent he had "full [aircraft] control to include tail rotor authority." The helicopter landed on the water and remained upright and afloat. The pilot further reported that he exited the helicopter after the blades came to a stop due to the "waves and wind." After moving away from the helicopter it rolled over. The pilot crawled onto the belly of the helicopter and waited to be rescued. The pilot stated that the wind was from 045 degrees at 15 knots gusting to 25 knots. An examination of the helicopter by the FAA inspector revealed that the tail rotor drive shaft was severed. Examination of the tail rotor drive shaft by an NTSB investigator revealed that the torsional twisting of the drive shaft was consistent with sudden stoppage of the tail rotor while the main rotor was driving. There was also evidence of a main rotor blade strike to the tail rotor drive shaft cover. Examination of the Allison 250-C20 turbine engine revealed that the N1 gas producer would not turn. A disassembly examination of the engine was conducted on January 17-18, 2001, at Dallas Airmotive of Dallas, Texas. During the examination the compressor coupling adapter was found fractured. The part was sent to the NTSB Materials Laboratory in Washington, D.C. for further examination. The examination of the compressor coupling adapter, P/N E23039791, S/N AG6-107, at the NTSB Materials Laboratory revealed fretting on the outer diameter surface where the impeller was press fit onto the adapter. The fretting was only present on the aft portion of the contact surface. Longitudinal scratches were observed around the circumference of the outer diameter surface. One scratch that was examined using scanning electron microscopy (SEM), showed smearing consistent with the aft movement of the compressor coupling adapter relative to the impeller, a relative motion consistent with the disassembly of the components. The aft fracture surface of the compressor coupling adapter was mostly obliterated by post fracture damage. The forward fracture surface had less post fracture damage. The fracture surface was relatively smooth, and crack arrest marks were observed, features typical of fatigue. The fracture was perpendicular to the outer surface and formed a shallow spiral around the longitudinal axis. The spiral was consistent with fatigue propagation with a clockwise (as viewed from aft) loading applied at the aft end relative to the forward end. The fatigue region was present nearly 360 degrees around the circumference. The fatigue features emanated from an origin area at the outer diameter surface in an area of fretting. Some deformation was observed on the faces of the hexagonal hole at the forward end of the compressor coupling adapter. No fretting was observed in that location. ## Aircraft - Registration: [N222LM](https://openairdocs.org/deregistered/N222LM-2006-01-09), registration cancelled 2006-01-09, S/N 1916 (OpenAirDocs) - Reported make and model: Bell 206B - Registry model: [Bell 206B](https://openairdocs.org/model/bell-206b) (registry code 1181511) (OpenAirDocs) - Category: Helicopter - Serial number: 1916 - Airframe hours: 20893 - Engines: Allison 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Positioning, Part 91 - Registered owner: American Helicopters, Inc. - Airworthiness certificate: Special, Restricted (Special) - Departed: MATAGORDA 603, GM - Destination: RKP - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; commercial; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 2,354 total, 707 in this make and model, 1,625 as pilot in command, 134 in the last 90 days, 39 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 45° at 15 knots, gusting 25 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 149 °F, dew point 140 °F - Altimeter: 30.00 inHg ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20001201023589A](https://openairdocs.org/incident/20001201023589A), Dec 1, 2000: Bell 206B, Rockport, TX, Substantial damage. (-23) On December 1, 2000, at 1625 CST, a Bell 206B helicopter, N222LN, was substantially damaged following a loss of engine power near Rockport, TX. The… ## Other investigations on N222LM (1) 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. - [NTSB FTW81FA020](https://openairdocs.org/ntsb/FTW81FA020), Dec 31, 1980: Bell 206B (N222LM), Patterson, LA, substantial damage 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.