# NTSB SEA94LA029: Bell 47G3B2, N8169J, Toledo, WA, November 9, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 9, 1993, 09:00 local (17:00 UTC) - Place: Toledo, WA - Coordinates: 46.449741, -122.759719 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.4497&lon=-122.7597&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 2, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 41852 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA94LA029 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41852/pdf - Page: https://openairdocs.org/ntsb/SEA94LA029 ## Probable cause TRANSMISSION SHEAR BOLTS FAILED CAUSING A LOSS OF POWER TO THE ROTOR SYSTEM, AND THE PILOT ENCOUNTERED UNSUITABLE TERRAIN DURING HIS AUTOROTATION ATTEMPT. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, maneuvering - rotor drive system,main gearbox/transmission - sheared (cause) - autorotation - attempted, pilot in command - Forced landing, descent - emergency - In flight collision with terrain/water, landing - flare/touchdown - object - tree(s) - terrain condition - none suitable (cause) ## Analysis WHILE LIFTING CHRISTMAS TREES UNDER EXTERNAL LOAD CONDITIONS THE PILOT HEARD A CLUNK AND EXPERIENCED A LOSS OF POWER. HE ATTEMPTED AN AUTOROTATION FROM 40 TO 50 FEET INTO THE CHRISTMAS TREE FARM, STRIKING AND BENDING THE TAIL BOOM WHEN IT IMPACTED A TREE. INVESTIGATION REVEALED THAT THE TRANSMISSION SHEAR BOLTS, PN 47-620-485-9, HAD SHEARED. THE PILOT ATTRIBUTED THE FAILURE OF THE SHEAR BOLTS TO POWER IMPULSES FROM REPEATED COMPRESSOR STALLS. ## Factual narrative On November 9, 1993, at 0930, a Bell B-47G3B2, N8169J, operated by Farm & Forest Helicopter Service, impacted terrain at Toledo, Washington, during an emergency forced landing. There was no flight plan filed for the local external load flight, conducted under 14 CFR 133, that was on takeoff from a field site when the accident occurred. The commercial certificated pilot was not injured in the accident. The aircraft was substantially damaged. There was no fire. The pilot reported he was on takeoff with an external load of Christmas trees when he heard a grinding sound and the main rotor RPM began to decrease. He initiated an autorotation from about 40 to 50 feet into the christmas trees. On landing, the tair boot hit a tree and bent. An examination of the wreckage revealed fractured main transmission shear bolts. The pilot attributed the failure to power impulses after repeated compressor stalls or partial flame-outs of the turbine engine. ## Aircraft - Registration: [N8169J](https://openairdocs.org/deregistered/N8169J-2009-09-23), registration cancelled 2009-09-23, S/N 6775, built 1970 (OpenAirDocs) - Reported make and model: BELL 47G3B2 - Registry model: [Bell 47G-3B-2](https://openairdocs.org/model/bell-47g-3b-2) (registry code 1181029) (OpenAirDocs) - Registry engine: [Allison 250 series](https://openairdocs.org/engine/allison-250-series) (registry code 03019, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 6775 - Airframe hours: 3013 - Engines: ALLISON 250-C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 133 - Operator: Farm & Forest Helicopter Svc - Registered owner: Farm & Forest Helicopter Svc - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, November 1, 1993, 27 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; private, commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 7,821 total, 952 in this make and model, 7,696 as pilot in command, 123 in the last 90 days, 36 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 225° at 2 knots, gusting 5 - Visibility: 10 statute miles - Lowest ceiling: 600 ft overcast - Temperature: 39 °F ## 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 19931109042759A](https://openairdocs.org/incident/19931109042759A), Nov 9, 1993: Bell 47G3B2, Toledo, WA, Substantial damage. On takeoff load of christmas trees. Grinding noise. Lost rotor RPM. Landed in trees. Main transmission bolts failed ## Other investigations on N8169J (2) 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 WPR09CA331](https://openairdocs.org/ntsb/WPR09CA331), Jul 7, 2009: Bell 47G-3B-2 (N8169J), Ocean Shores, WA, substantial damage. Probable cause: The pilot's failure to maintain clearance from the water while maneuvering due to the pilot's diverted attention. - [NTSB SEA74DYG50](https://openairdocs.org/ntsb/SEA74DYG50), Jun 23, 1974: Bell 47G3B2 (N8169J), Clarkston, WA, destroyed 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.