# NTSB SEA06LA114: Beech A36, N24BF, Ennis, MT, June 6, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 5, 2006, 19:00 local (Jun 6, 2006, 01:00 UTC) - Place: Ennis, MT - Coordinates: 45.271667, -111.648612 - Nearby events: https://openairdocs.org/map.md?lat=45.2717&lon=-111.6486&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report March 26, 2007 - Report: Approved by Office Director - Parties: Continental Engines, FAA Helena, Montana, FSDO - NTSB case key (mKey): 63875 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA06LA114 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/63875/pdf - Page: https://openairdocs.org/ntsb/SEA06LA114 ## Probable cause The loss of engine power during takeoff due to an excessively lean fuel-to-air mixture ratio as a result of excessive mating surface wear between the mixture control arm and metering shaft. A factor was the improper installation of the new engine, which resulted in excessive wear and metering of fuel and loss of engine power. An additional factor was the rough, uneven terrain. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, takeoff - maintenance,installation - improper, company maintenance personnel (contributing factor) - mixture control,linkage - failure,partial (cause) - Forced landing, emergency descent/landing - Wheels up landing, emergency landing - On ground/water encounter with terrain/water, emergency landing - terrain condition - rough/uneven (contributing factor) ## Analysis The pilot reported that shortly after takeoff the airplane lost engine power and he elected to land in an open field south of the airport. Post accident evaluation and testing of the mixture control linkage revealed that the metering shaft rotated to the mechanical stop when actuated to the "idle cut-off" position; however, when the mixture control was actuated to the "full-rich" position, the metering shaft rotated approximately 40 percent of potential (full) travel and did not reach the mechanical stop. Further examination revealed the mixture control arm retaining nut was tight, however extensive wear to the serrated mating surfaces of the mixture control arm and metering shaft was observed. The serrated edges had worn smooth and fretting type damage was noted to both surfaces. Maintenance records showed that the airplane's original engine, a Continental IO-520, was removed and the airframe was retrofitted with a factory rebuilt (zero time) IO-550-B in accordance with a Supplemental Type Certificate (STC). The certified airframe and power plant (A&P) mechanic, who performed the maintenance on the airplane, stated the mixture control arm (which was shipped with the engine) was installed in conjunction with the engine conversion. ## Factual narrative On June 5, 2006, about 1900 mountain daylight time, a Beech A36 Bonanza, N24BF, sustained substantial damage following a loss of engine power and subsequent forced landing approximately two miles south of the Ennis - Big Sky Airport (KEKS), Ennis, Montana. The airplane, which was owned by the pilot, was being operated as a visual flight rules (VFR) cross-country flight under the provisions of Title 14, CFR Part 91, when the accident occurred. The certificated private pilot, and three passengers, were not injured. Visual meteorological conditions prevailed for the cross-country flight that originated from Ennis just before the accident. The pilot's planned destination was Hamilton, Montana. The pilot reported that shortly after takeoff, the airplane lost engine power and he elected to land in an open field south of the airport. The airplane sustained substantial damage to the firewall during the landing. On June 27, 2006, representatives from the Federal Aviation Administration (Helena, Montana, Flight Standards District Office) and Teledyne Continental Motors examined the airplane at a hangar facility in Belgrade, Montana. Functional testing of the mixture control linkage revealed that the metering shaft rotated to the mechanical stop when actuated to the "idle cut-off" position; however, when the mixture control was actuated to the "full-rich" position, the metering shaft rotated approximately 40 percent of potential (full) travel and did not reach the mechanical stop. Further examination revealed the mixture control arm retaining nut was tight, however extensive wear to the serrated mating surfaces of the mixture control arm and metering shaft was observed. The serrated edges had worn smooth and fretting type damage was noted to both surfaces. Maintenance records showed that on March 9, 2006, the airplane's engine, a Continental IO-520, was removed and the airframe was retrofitted with a factory-rebuilt IO-550-B in accordance with Supplemental Type Certificate (STC) SA2200SW. The mixture control arm was shipped with the factory-rebuilt engine. The certified airframe and power plant (A&P) mechanic, who performed the maintenance on the airplane, stated the mixture control arm was installed in conjunction with the engine conversion. The airplane had accumulated approximately 35 hours since the conversion. ## Aircraft - Registration: [N24BF](https://openairdocs.org/aircraft/N24BF), registered now, S/N E1736, built 1980 (OpenAirDocs) - Reported make and model: Beech A36 - Registry model: [Beech A36](https://openairdocs.org/model/beech-a36) (registry code 1151604) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: E1736 - Airframe hours: 3465 - Engines: Continental IO-550B 300 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: David A. Nicely - Airworthiness certificate: Standard, Utility; Standard, Normal - Last inspection: Annual, March 1, 2006, 35 hours before - Departed: KEKS, Ennis, MT - Destination: 6S5, HAMILTON, MT - Airport: KEKS, Ennis - Big Sky, runway 16, 4,694 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review May 1, 2006; seat: left; flight hours: 1,800 total, 700 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none ## 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 20060605013409A](https://openairdocs.org/incident/20060605013409A), Jun 5, 2006: Beech A36, Ennis, MT, Minor damage. (-23) Pilot stated that soon after take-off, the engine started losing power and he was unable to climb. He attempted to adjust the mixture when the engine… 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.