# NTSB SEA06LA133: Nanchang China CJ-6, N8120H, Brewster, WA, July 3, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 2, 2006, 18:50 local (Jul 3, 2006, 01:50 UTC) - Place: Brewster, WA - Coordinates: 48.104721, -119.730003 - Nearby events: https://openairdocs.org/map.md?lat=48.1047&lon=-119.7300&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 26, 2007 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 64085 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA06LA133 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/64085/pdf - Page: https://openairdocs.org/ntsb/SEA06LA133 ## Probable cause The failure of the engine's three planetary gears for undetermined reasons. A factor contributing to the accident was the tree orchard. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - normal - reduction gear assy - failure (cause) - Forced landing, emergency descent/landing - In flight collision with object, maneuvering - object - tree(s) (contributing factor) ## Analysis While in cruise flight at 5,000 feet the pilot heard a loud bang, followed by an instantaneous increase in RPM. Subsequent attempts to sustain engine power with throttle and propeller inputs were unsuccessful, which resulted in the pilot attempting a forced landing to a paved runway approximately 4 miles away. The airplane subsequently impacted the last row of trees of an orchard less than one-half mile from the end of the runway, which resulted in the airplane coming to rest on its belly oriented on an easterly heading. A post accident examination of the airplane's engine revealed that all three planetary gears were severely damaged, and all three gears appeared to have lost all gear teeth, with a portion of the gear teeth located in the oil sump. The reason for the damage to the planetary gears was not determined. ## Factual narrative On July 2, 2006, approximately 1850 Pacific daylight time, a single-engine Nanchang China CJ-6 experimental airplane, N8120H, sustained substantial damage after impacting terrain following a loss of engine power and a forced landing approximately one-half mile west of Anderson Field (S97), Brewster, Washington. The airplane is registered to a private individual. The certificated private pilot, sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed for the personal cross-country flight, which was operated in accordance with 14 CFR Part 91, and a flight plan was not filed. The flight departed the Arlington Municipal Airport (AWO), Arlington, Washington, about 1800, with its destination being the Omak Airport, Omak, Washington. According to the Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1), the pilot reported that while in cruise flight about 5,000 feet mean sea level and approximately 3 or 4 nautical miles west of S97, he heard a "loud pop" followed by an "instantaneous increase" in [propeller] revolutions per minute (RPM), to over 4,000 RPM. The pilot further reported that after the engine would not respond to throttle or propeller [control] inputs, he set up the best rate [of descent] speed for a straight in approach in an attempt to reach Runway 07 at S97. The pilot stated that he approached the airstrip at just above stall speed and elected to delay lowering the landing gear until he cleared the tree orchard, located less than one-half mile from the end of runway 07. The pilot revealed that the airplane settled into the last row of trees before coming to rest on its belly about 10 to 15 feet past the orchard, and oriented in an easterly direction. A post accident examination of the airplane revealed that the airplane had sustained substantial damage to both wings, the right wing tip, and the horizontal stabilizer. Damage was also observed to the engine cowling, propeller and the airplane's belly skin. A subsequent examination of the engine by the pilot, who advised the NTSB investigator-in-charge that he had 15 years experience working on and operating the Housia HS6, revealed that the propeller "free wheeled" without any evidence of connection to the engine crankshaft. The pilot reported that after the engine cowling was removed there was no external damage observed to the engine. The pilot further reported that after the propeller governor, propeller, shutters and nose case were removed, it was revealed that inside the nose case the three planetary gears were found to be severely damaged; all three appeared to have lost all [gear] teeth. The pilot stated that a portion of the broken gears was later recovered in the oil sump. The pilot further stated that during the examination the engine was found to have continuity between all accessories, pistons, valve train and the main crankshaft. The pilot reported that he could offer no reason for the failure of the planetary gears. ## Aircraft - Registration: [N8120H](https://openairdocs.org/deregistered/N8120H-2017-04-18), registration cancelled 2017-04-18, S/N 48-21, built 1989 (OpenAirDocs) - Reported make and model: Nanchang China CJ-6 - Registry model: [Nanchang China CJ-6](https://openairdocs.org/model/nanchang-china-cj-6) (registry code 05628VC) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane - Serial number: 48-21 - Airframe hours: 2112 - Engines: Housia HS6 285 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 1, 2006, 7 hours before - Departed: AWO, Arlington, WA - Destination: OMK, Omak, WA - Airport: S97, Anderson Field, runway 07, 4,000 × 60 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; injuries: none; private; airplane ratings: single-engine sea, single-engine land; medical: class 3, with waivers/limitations; last flight review July 1, 2004; seat: front; flight hours: 1,384 total, 65 in this make and model, 1,321 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 34 °F - Altimeter: 29.93 inHg - Observed at: OMK, 20 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 20060702012939A](https://openairdocs.org/incident/20060702012939A), Jul 2, 2006: Nancng CJ6, Brewster, WA, Substantial damage. (-23) During cruise flight, pilot heard/felt a couple of bangs, engine RPM increased to 4000 and quit. Pilot elected to attempt landing at Anderson field… 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.