# NTSB SEA95LA119: Grumman G-164B, N6669Q, Helena, MT, June 15, 1995 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 15, 1995, 10:30 local (16:30 UTC) - Place: Helena, MT - Coordinates: 46.529605, -112.210762 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=46.5296&lon=-112.2108&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report January 29, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 42166 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA95LA119 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/42166/pdf - Page: https://openairdocs.org/ntsb/SEA95LA119 ## Probable cause THE LOSS OF ENGINE POWER FOR UNDETERMINED REASONS. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, maneuvering - aerial application - reason for occurrence undetermined (cause) - engine assembly,cylinder - cracked - engine assembly,crankshaft - overtemperature - engine assembly,crankshaft - binding(mechanical) - In flight collision with terrain/water, maneuvering - aerial application - terrain condition - crop ## Analysis WHILE MANEUVERING IN CLOSE PROXIMITY TO THE GROUND, THE ENGINE BACKFIRED TWO OR THREE TIMES AND SUDDENLY LOST POWER. THE PILOT ATTEMPTED TO LEVEL THE WINGS AND EXECUTE A FORCED LANDING, BUT THE AIRPLANE IMPACTED TERRAIN IN A BANK. EXAMINATION OF THE ENGINE REVEALED THAT THE CRANKSHAFT WAS BINDING DURING ROTATION, THE NO. 5 CYLINDER HEAD WAS CRACKED, AND THE CRANKSHAFT WAS EXPOSED TO HEAT DISTRESS. NO EVIDENCE WAS FOUND TO INDICATE THAT THESE DEFICIENCIES OCCURRED AFTER THE ACCIDENT. POSTIMPACT AND THERMAL DAMAGE TO THE ENGINE PRECLUDED A COMPLETE FUNCTIONAL TEST AND EXAMINATION OF THE ENGINE. ## Factual narrative On June 15, 1995, about 1030 hours mountain daylight time, N6669Q, a Grumman G-164B airplane, operated by the owner/pilot, impacted terrain while maneuvering near Helena, Montana. The airplane was destroyed. There was a post crash fire. The commercial pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight was conducted under 14 CFR 137. According to an FAA aviation safety inspector from Helena, the pilot stated that he was in the process of maneuvering close to the ground during an agricultural aerial application when the engine "... lost partial power." The pilot stated that he was not able to sustain enough engine power to prevent the airplane from descending into terrain during the maneuver. The airplane impacted terrain and burned. The pilot stated in writing to the Safety Board that the engine "... backfired 2 [or] 3 times...then quit." He also stated that he attempted to level the wings and perform a forced landing, but the airplane was too close to the ground to do so. According to airframe and engine maintenance logs, the airframe and engine received an annual inspection on March 30, 1995. No unresolved discrepancies were found. The recorded tachometer time of the engine at the time of the inspection was 3,074 hours. The engine had received a major overhaul about 400 operating hours prior to the accident. The engine was removed from the wreckage, partially disassembled, and inspected by FAA aviation safety inspectors from Helena. According to their report (attached): ... the number 5 cylinder had a gaping crack running from the forward spark plug port, across the upper cylinder head, and engine at the rear spark plug port. This crack appeared to have existed for a period of time prior to the accident and was not a result of the accident. The report also stated: ... examination of the interior area of the engine disclosed the crankshaft at the forward bearing area showed bluing discoloration. Binding was noted when the crankshaft was rotated. This discoloration was not a result of the fire in the rear of the engine. ## Aircraft - Registration: [N6669Q](https://openairdocs.org/deregistered/N6669Q-2009-03-24), registration cancelled 2009-03-24, S/N 191B, built 1977 (OpenAirDocs) - Reported make and model: GRUMMAN G-164B - Registry model: [Grumman Acft ENG Cor-Schweizer G-164B](https://openairdocs.org/model/grumman-acft-eng-cor-schweizer-g-164b) (registry code 3952802) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 191B - Airframe hours: 3200 - Engines: P&W 1340-AN1 600 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Aerial application, Part 137 - Registered owner: Morgan, Boyd J. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, March 30, 1995 ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: front; flight hours: 5,889 total, 1,800 in this make and model, 5,889 as pilot in command, 100 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 60° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 68 °F, dew point 54 °F - Altimeter: 29.00 inHg - Observed at: HLN, 18 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 19950615045439A](https://openairdocs.org/incident/19950615045439A), Jun 15, 1995: Scwzer G164B, Helena, MT, Destroyed. Lost power on spray turn around. Impacted and burned. 400 hrs on engine tbo. Cylinder head prior crack. Oil lost. 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.