# NTSB ANC93FA064: Fairchild FH-1100, N5060F, Malina Bay, AK, May 17, 1993 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Field investigation · Final report - Date: May 17, 1993, 14:15 local (22:15 UTC) - Place: Malina Bay, AK - Coordinates: 57.789897, -152.400405 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=57.7899&lon=-152.4004&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 2 serious, 2 minor - Status: Completed, report June 30, 1994 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 2301 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC93FA064 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2301/pdf - Page: https://openairdocs.org/ntsb/ANC93FA064 ## Probable cause THE INSTALLATION OF A BOGUS TRANSMISSION TO ENGINE DRIVESHAFT. THE FAILURE OF THE COMPANY MAINTENANCE PERSONNEL TO COMPLY WITH THE SERVICE BULLETINS AND LETTERS WAS A FACTOR. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, climb - rotor drive system,engine to transmission drive - unapproved part (cause) - maintenance,service bulletin/letter - not maintained, company maintenance personnel (contributing factor) - Forced landing, descent - emergency ## Analysis EXAMINATION OF THE HELICOPTER SHOWED THAT THE ENGINE TO TRANSMISSION DRIVE SHAFT, ENGINE SIDE COUPLING FAILED. METALLURGICAL ANALYSIS SHOWED FATIGUE FRACTURE SURFACES BUT DUE TO THE ROTATIONAL DAMAGE, THE ORIGIN OF THE FRACTURE COULD NOT BE DETERMINED. THE EXAMINATION ALSO SHOWED MANY STAMPED NUMBERS PEENED OVER WITH A DIFFERENT NUMBER. HOWEVER, THE BENDIX DATA PLATE WAS STILL AFFIXED TO THE SHAFT AND SHOWED THE PART NUMBER 19E49-3E. EXAMINATION OF THE HELICOPTER RECORDS SHOWED THAT A DIFFERENT SERIAL NUMBERED SHAFT WAS SUPPOSED TO BE INSTALLED. ACCORDING TO THE SERVICE RECORD OF THE SHAFT ACTUALLY INSTALLED, IT DID NOT SEE ANY SERVICE FROM JULY, 1978 TO MARCH, 1992. DOCUMENTATION WAS NOT FOUND SHOWING THE DRIVE SHAFT HAD BEEN MAINTAINED IN ACCORDANCE WITH APPLICABLE SERVICE LETTERS AND BULLETINS. ## Factual narrative HISTORY OF FLIGHT On May 17, 1993, at 1415 Alaska daylight time, a float equipped FH 1100 helicopter, N5060F, registered to Tom Walters, and operated by Sea Hawk, Inc., of Kodiak, Alaska, crashed into trees while attempting to execute a forced landing. The air taxi flight, operating under 14 CFR Part 135, departed Kodiak Municipal Airport on a company visual flight rules flight plan, and the destination was Malina Lake, near Malina Bay, on Afognak Island, Alaska. Visual meteorological conditions prevailed. The helicopter was substantially damaged and the Pilot-in-Command and the three passengers were seriously injured. According to the Pilot in Command, they had just made a low pass over an archeological site on the beach and were climbing over rising terrain and trees. The pilot heard a bang and immediately began to lose rotor RPM. He turned left to reach a small clearing and struck the tree tops at the edge of the clearing. The helicopter impacted the ground at the base of the trees. TEST AND RESEARCH The on site examination of the helicopter showed that the engine to transmission drive shaft assembly rotated freely in both directions. Subsequent metallurgical examination showed that the coupling on the engine end of the shaft failed as a result of fatigue cracking in the forward diaphragm. According to the Metallurgist, the location of fatigue initiation could not be determined due to the extensive post fracture rotational damage. Examination of the aircraft logbooks revealed the following information. The engine to transmission drive shaft, part number PN 19E49-3, serial number 2652 U, was installed on N5060F on June 1, 1990. Component time on this shaft was shown in the log book as Time since overhaul 962.9 hours. The logbook also shows that end pack assemblies, serial number 757AP and 711AP were installed and each had a total time 962.9 hours. Examination of the helicopter showed that the engine to transmission drive shaft that was actually installed was part number 19E49-3E, serial number 2717-U. The helicopter records contained a service record book which had this shaft's service record. The service record shows that shaft serial number 2717-U was removed in July 1978 with a total time of 140.0 hours. The next entry on the service record shows it was installed on helicopter serial number 242 in March, 1992 with a total time of 140 hours. The service record also shows that the end pack assemblies installed with this shaft were serial number 725 AP and 749 AP. The helicopter had 2669.9 hours total time when shaft number 2717-U was installed. The total time on the helicopter at the time of the accident was 2758.6 hours. The records further fail to show whether or not any of the following service bulletins or letters had been accomplished. Service Letter FH1100-24-5A Service Letter FH1100-24-6 Service Letter FH1100-24-7 Service Letter FH1100-24-9 Service Letter FH1100-24-10 Service Bulletin FH1100-24-7 Examination of the engine to transmission drive shaft (short shaft) shows that Service Letter FH1100-24-7 which outlined the procedures for installing vent plates, part number 2489839, was not accomplished. The reason for the Service Letter was to "vent the diaphragm packs to atmosphere to stabilize wear of the carbon sockets." Neither diaphragm pack had the vented plates installed. Service Letter FH1100-24-10 calls for an application of a Dow Corning coating to the diaphragms. Examination of the surfaces of the fractured diaphragm showed that a coating existed however, it could not be determined to be a Dow Corning coating. Examination of the short shaft center section revealed a variety of markings. One marking was an arrow indicating the direction of forward. The easily visible arrow indicated the correct direction. Beneath that arrow, another arrow, faintly visible under magnification shows the forward in the opposite direction. The metallurgical examination revealed other numbers peened over different numbers. The shaft had a Bendix data plate attached to the aft, center section of the shaft which showed the part number 19E49-3E and serial number 2717-U. A review of the Operator's "Operations Specifications," showed no requirement to comply with the Service Letters or the Service Bulletins. Examination of the lower isolation snubber mount of the transmission showed that the mount was worn and had become spongy. The mount is made of rubber and has square holes along its edges. The corners of these holes were starting to crack to lengths of 1/4 of an inch. According to Alaska Helicopters Maintenance, the isolation mount limits the movement of the transmission. When the mount becomes worn, the transmission may move in any direction more than normal and cause stress to be applied to the transmission to engine driveshaft. Alaska Helicopters has owned and operated FH100 helicopters under 14 CFR Part 135, however, they no longer operate any FH1100 helicopters. ADDITIONAL INFORMATION The Pilot-in-Command purchased the helicopter from Clearwater Helicopters in Florida. Clearwater Helicotpers was formerly Tampa Bay Helicopters. ## Aircraft - Registration: [N5060F](https://openairdocs.org/deregistered/N5060F-2014-10-14), registration cancelled 2014-10-14, S/N 242, built 1971 (OpenAirDocs) - Reported make and model: FAIRCHILD FH-1100 - Registry model: [Fairchild Hiller FH-1100](https://openairdocs.org/model/fairchild-hiller-fh-1100) (registry code 3376502) (OpenAirDocs) - Registry engine: [Allison 250 SER 250HP](https://openairdocs.org/engine/allison-250-ser-250hp) (registry code 03002, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 242 - Airframe hours: 2759 - Engines: Allison 250-C18 274 horsepower turbo shaft - Damage: Substantial damage - Flight: Part 135 - Operator: Sea Hawk, Inc. - Registered owner: Walters, Thomas - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 1, 1992, 100 hours before - Departed: KDK, KODIAK, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; commercial, private; airplane ratings: single-engine land, single-engine sea; instrument ratings: airplane, helicopter; medical: class 2, valid medical--no waivers/lim.; seat: right; toxicology performed; flight hours: 7,000 total, 100 in this make and model, 6,500 as pilot in command, 75 in the last 90 days, 30 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 30 statute miles - Lowest ceiling: none - Temperature: 70 °F - Altimeter: 29.00 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 19930517017109A](https://openairdocs.org/incident/19930517017109A), May 17, 1993: Hiller FH1100, Malina Bay, AK, Substantial damage. Bang and lost rotor RPM. Struck trees. Coupling on drive short shaft failed. Poor improper maintenance were factors ## Other investigations on N5060F (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 SEA76DYE07](https://openairdocs.org/ntsb/SEA76DYE07-149983), Aug 8, 1975: Hiller Acft FH1100 (N5060F), Shelton, WA, 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.