# NTSB ANC98LA099: Cessna 207, N1763U, King Salmon, AK, July 17, 1998 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 16, 1998, 17:25 local (Jul 17, 1998, 01:25 UTC) - Place: King Salmon, AK - Coordinates: 58.749328, -156.540176 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=58.7493&lon=-156.5402&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report October 30, 2001 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - NTSB case key (mKey): 43068 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC98LA099 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43068/pdf - Page: https://openairdocs.org/ntsb/ANC98LA099 ## Probable cause The disconnection of the mixture control cable from the mixture control arm. Factors associated with this accident were the inadequate 100 hour inspections performed by company mechanics. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, cruise - mixture control,cable - disconnected (cause) - maintenance,100-hour inspection - inadequate, company maintenance personnel (contributing factor) - miscellaneous,bolt/nut/fastener/clamp/spring - inadequate (contributing factor) - Loss of engine power(total) - mech failure/malf, maneuvering - turn to landing area (emergency) - Forced landing, descent - emergency - Nose over, emergency landing - terrain condition - tundra ## Analysis The pilot had leveled off in cruise and was leaning the fuel mixture when the mixture control ceased to have effect. The pilot stated that the engine began to lose power, then quit. The airplane nosed over during the forced landing in tundra. Postaccident inspection revealed the mixture control cable had unscrewed from the mixture control arm. The cable had been replaced 238 hours prior to the accident, and was inspected 142, and 44 hours prior to the accident. The service manual specified the jam nut that locked the cable to the arm be torqued to 15 +/- 2 inch-pounds. There was no safety wire requirement for this linkage. If disconnected, gravity would allow the mixture control arm to fail to idle-cutoff. ## Factual narrative On July 16, 1998, at 1725 Alaska daylight time, a Cessna 207 airplane, N1763U, sustained substantial damage when it nosed over during a forced landing 7 miles south of the King Salmon Airport, King Salmon, Alaska. The solo commercial pilot sustained minor injuries. The flight was operated under 14 CFR Part 135 by Yute Air Alaska, Inc., of Anchorage, Alaska, as a nonscheduled cargo flight. The flight departed King Salmon at 1720, transporting bypass mail to Egegik, Alaska. Visual meteorological conditions prevailed at the time of the accident, and a company VFR flight plan was filed. The pilot told the NTSB investigator on July 16, 1998, that he leveled off to cruise at 700 feet msl, and began to lean the engine's mixture control. He said that about 10 miles south of King Salmon, the mixture control stopped having an effect on engine operation, and the engine began to lose power. While turning towards the airport, the engine lost total power, and he performed an emergency landing. During landing, the airplane nosed over. Postaccident inspection revealed that the mixture control arm had unscrewed from the mixture control cable. The Cessna 207 Service Manual specifies the jam nuts which attach the cable to the control be torqued to 15 inch-pounds, plus or minus 2 inch-pounds. There is no safety wire required in the installation. A review of the engine maintenance records indicated that the engine had received 100 hour inspections 44 hours, and 142 hours, prior to the accident. On both these occasions, Service Bulletin SEB95-15R1 (Throttle Control Lever Inspection) was performed. This lever is located next to the disconnected mixture control arm linkage. The mixture control cable was replaced 238 hours prior to the accident. Inspection of a representative C-207 installation by the NTSB investigator-in-charge revealed that if the mixture control arm becomes disconnected, gravity allows the arm to fall to the lean / idle-cutoff position. ## Aircraft - Registration: [N1763U](https://openairdocs.org/deregistered/N1763U-2018-01-11), registration cancelled 2018-01-11, S/N 20700363, built 1976 (OpenAirDocs) - Reported make and model: Cessna 207 - Registry model: [Cessna 207A](https://openairdocs.org/model/cessna-207a) (registry code 2073604) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 20700363 - Airframe hours: 14529 - Engines: Continental IO-520-F27B 285 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Registered owner: Yute Air Alaska, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, July 3, 1998, 44 hours before - Departed: AKN - Destination: EII, EGEGIK, AK - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 64; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 14,000 total, 4,000 in this make and model, 14,000 as pilot in command, 230 in the last 90 days, 105 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: 3,200 ft broken - Temperature: 61 °F, dew point 48 °F - Altimeter: 29.00 inHg - Observed at: AKN, 10 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 19980716016679A](https://openairdocs.org/incident/19980716016679A), Jul 16, 1998: Cessna 207A, King Salmon, AK, Substantial damage. (.4)The pilot had leveled off in cruise and was leaning the fuel mixture when the mixture control ceased to have effect. The pilot states that the engine began… ## Other investigations on N1763U (4) 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 ANC93LA072](https://openairdocs.org/ntsb/ANC93LA072), May 29, 1993: Cessna 207 (N1763U), Bethel, AK, substantial damage. Probable cause: THE PILOT'S FAILURE TO MAINTAIN CONTROL OF THE AIRPLANE DURING LANDING. - [NTSB ANC88LA146](https://openairdocs.org/ntsb/ANC88LA146), Sep 22, 1988: Cessna 207A (N1763U), New Koliganek, AK, substantial damage - [NTSB ANC87LA015](https://openairdocs.org/ntsb/ANC87LA015), Nov 19, 1986: Cessna 207A (N1763U), Manokotak, AK, substantial damage - [NTSB FTW78FRD47](https://openairdocs.org/ntsb/FTW78FRD47-196844), May 26, 1978: Cessna 207A (N1763U), Brownsville, TX, substantial damage 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.