# NTSB SEA96FA076: Bell UH-1H, N6166R, Rainier, WA, April 4, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Field investigation · Final report - Date: April 4, 1996, 08:20 local (16:20 UTC) - Place: Rainier, WA - Coordinates: 46.869796, -122.660331 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.8698&lon=-122.6603&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 28, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 42274 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA96FA076 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42274/pdf - Page: https://openairdocs.org/ntsb/SEA96FA076 ## Probable cause failure of the forward power shaft (number 21) bearing. A factor relating to the accident was: the lack of suitable, unobstructed terrain for an emergency 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, maneuvering - engine assembly,bearing - failure,total (cause) - Forced landing, emergency descent/landing - autorotation - performed, pilot in command - In flight collision with terrain/water, emergency landing - terrain condition - none suitable (contributing factor) ## Analysis While preparing to sling a load of logs, the pilot noticed several changes in engine noise level followed by two loud bangs and a total loss of power. He executed an autorotation/landing into a small clearing directly beneath the rotorcraft as no other suitable site was available. During the forced landing, the helicopter was damaged. Disassembly of the ex-military, Allied Signal (Lycoming) T53-L-13BA turboshaft engine revealed that the number 21 forward bearing (P/N 1-300-082-01B) had disintegrated. The engine had a total of 4202.4 operating hours of which 199.4 were accrued since entering the civilian operating environment. Nonmandatory Service Bulletin No. 0056 provided procedures for replacing this bearing with an improved bearing (P/N 1-300-082-03), within 400 hours after receipt of the bulletin. ## Factual narrative HISTORY OF FLIGHT On April 4, 1996, approximately 0820 Pacific standard time, a Garlick HH-1K (formerly a military Bell UH-1H) restricted category rotorcraft, N6166R, registered to and operated by Northwest Helicopters, Inc., and being flown by a commercial pilot, was substantially damaged upon impact with terrain during an auto-rotative emergency landing following a total loss of power. The rotorcraft crashed approximately 11 miles southeast of Rainier, Washington. The pilot was uninjured and variable meteorological conditions existed at the time. The rotorcraft, which was engaged in logging, was to have been operated under 14CFR133, and originated from a point near the accident site approximately 35 minutes prior to the accident. The pilot reported that the rotorcraft had been engaged in log lifting operations when he "noticed a minute change in noise level." After adjusting the power he determined that "everything seemed normal" and then lowered the log sling line in preparation for another log lift. He reported that "at that time the noise level changed again" and he then began to maneuver to return to the service landing site. He was then radioed by the ground crewman of smoke coming from the rotorcraft's exhaust and noted that the master caution light had illuminated. The pilot reported hearing two loud bangs and observed the EGT, N1, N2, and NR all begin to unwind. Immediately thereafter, he "looked for a landing area and found only a hole in the timber right below" and then executed an auto-rotation into that site. AIRCRAFT INFORMATION The rotorcraft was equipped with an Allied Signal (Lycoming) model T53-L-13BA turboshaft engine, serial number LE15957. Although this was a military model number designation and the equivalent commercial model number designation is T53-13B, the data plate affixed to the engine was that for a commercial engine rather than a military data plate. The "A" suffix on the model number is a military designation pertaining to the fuel control configuration. The information on the data plate was observed to have been applied with a vibro-peen type tool. It could not be determined at what point in the engine's history the military data plate was removed and replaced with the civilian data plate. The engine was manufactured in 1967 and was obtained from the military by the operator in early 1993 with 4003.0 hours total time since new. The engine was first installed in N6166R on January 8, 1996, with the same total time. According to maintenance records, the engine had accumulated 4202.4 hours total time since new, and 1252.4 hours time since last overhaul at the time of the accident. The total time on the number 21 forward bearing could not be determined. The bearing had not been changed subsequent to the engine's leaving military service and the total civil engine time was 199.4 hours. ADDITIONAL INFORMATION The engine was partially disassembled at the facilities of Allied Signal Aerospace, Phoenix, Arizona, on July 2, 1996. The disassembly results were reported in Allied Signal report number 21-9263, and revealed that the number 21 forward bearing, P/N USA FP96 1-300-082-01B, had disintegrated. The roller bearings were observed to be heavily deformed and the forward (geared) end of the accessory drive shaft had separated from the remainder of the shaft thus depriving the fuel pump of rotational input. The oil within the engine was observed to be generally clear but with particulates suspended within. Avco Lycoming Service Bulletin No. 0056, which was issued August 28, 1986, and applies to T53-L-13 series engines that are non-U.S. military, was issued to "introduce forward power shaft bearing 1-300-082-03 having improved reliability." The service bulletin provided instructions for replacing the forward power shaft bearing and was to be accomplished on "engines within 400 operating-hours after receipt of (the) bulletin." Verbal release of the engine was provided to Mr. Steven Macon of Allied Signal on August 11, 1996, and written wreckage release was accomplished on September 20, 1996 (refer to attached NTSB Form 6120.15). ## Aircraft - Registration: [N6166R](https://openairdocs.org/deregistered/N6166R-2002-06-20), registration cancelled 2002-06-20, S/N 157199, built 1995 (OpenAirDocs) - Reported make and model: Bell UH-1H - Registry model: [Bell UH-1H](https://openairdocs.org/model/bell-uh-1h) (registry code 1181407) (OpenAirDocs) - Registry engine: [Lycoming T53-L-13](https://openairdocs.org/engine/lycoming-t53-l-13) (registry code 41551, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 157199 - Airframe hours: 5020 - Engines: Lycoming T53-L-13BA 1400 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 133 - Registered owner: Northwest Helicopters, Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: 100 hour, March 29, 1996, 7 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 39; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 5,000 total, 1,990 in this make and model, 4,788 as pilot in command, 188 in the last 90 days, 49 in the last 30 days, 6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 0.75 statute miles - Lowest ceiling: 300 ft broken - Temperature: 43 °F, dew point 43 °F - Altimeter: 30.00 inHg - Observed at: OLM, 22 nm away ## 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 19960404006049A](https://openairdocs.org/incident/19960404006049A), Apr 4, 1996: Bell UH1H, Rainier, WA, Substantial damage. Loud bang from engine and smoke. Autorotated into trees. Forward shaft bearing disintegrated. Sb on it not complied 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.