# NTSB ERA22LA358: Cessna 207, N6908M, Dillingham, AK, July 28, 2022 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 27, 2022, 17:25 local (Jul 28, 2022, 01:25 UTC) - Place: Dillingham, AK - Coordinates: 59.044667, -158.5055 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=59.0447&lon=-158.5055&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 105670 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA22LA358 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105670/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105670 - Page: https://openairdocs.org/ntsb/ERA22LA358 ## Probable cause Maintenance personnel’s failure to detect and correct improper rudder control system alignment, the resulting interference with the pulley’s rotation, and the accelerated corrosion and wear of the control cable, which ultimately led to its failure in flight. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Cessna 207A, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=2073605), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Flight control system: rudder control system](https://openairdocs.org/ntsb-findings/01022720): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Cessna 207A, 1 case](https://openairdocs.org/ntsb-findings/01022720/cases.md?model=2073605), [All aircraft, 93 cases](https://openairdocs.org/ntsb-findings/01022720/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) (defining event); cases with it: [Cessna 207A, 1 case](https://openairdocs.org/ntsb-events/333/sequence.md?model=2073605), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md) ## Analysis The pilot reported that, during approach to landing, he became aware that the left rudder pedal was not responsive. He declared an emergency and landed uneventfully. Examination revealed that the left rudder cable fractured due to corrosion and severe cable wear at the left pulley location. Nearly all wires on the cable were worn to a chisel-like point, leaving a small number of wires in the core strand to fracture in ductile overstress during final separation. The cable corrosion and wear were likely accelerated due to sliding contact with the left pulley. Issues with the rudder control system installation were evident on both pulleys. Rubbing damage on the face of the left pulley indicated that the pulley was contacting adjacent structure at the outer diameter. This contact likely interfered with pulley rotation, leading to the accelerated corrosion and wear of the control cable from sliding contact within the pulley groove. Although no rubbing damage was observed on the right pulley, the cable contact pattern was offset from the groove centerline, indicating an alignment problem in the rudder control system at the right pulley. Review of the maintenance logs revealed that the last inspection of the flight controls was completed about 8 months before the accident, and an entry about 3 months later noted a stuck pulley and corrosion of the left rudder cable. The maintenance response to the entry stated, “upon further inspection, determined cable not corroded. . . No defects.” Given the findings of the postaccident examination, it is likely that the accident would have been prevented had maintenance personnel taken more proactive action at that time. ## Factual narrative On July 27, 2022, about 1725 Alaska daylight time, a Cessna 207A, N6908M, was substantially damaged when it was involved in an accident near Dillingham, Alaska. The pilot and two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 135 scheduled flight. The pilot reported that, during approach to landing he became aware that the left rudder pedal was not responsive. The pilot declared an emergency and landed uneventfully. Examination of the airplane by a Federal Aviation Administration inspector revealed that one of the rudder cables had fractured, and rust was visible at the fracture location. Because the failure of the rudder cable adversely affected the performance and flight characteristics of the airplane and required replacement of the cable, the damage to the airplane was substantial. Follow-up examination revealed that the rudder cable was fractured about 94 inches from the turnbuckle terminal end and 152 inches from the center of the attachment holes in the clevis at the other end. The bearings at the centers of the pulleys moved freely in both submitted pulleys; however, examination revealed abrasion of the outer rim of the left pulley and orange deposits consistent with rust in the groove for the left pulley in addition to rubbing around much of the circumference of the groove contact surface. Although no rubbing damage was observed on the right pulley, the cable contact pattern was offset from the groove centerline. The fractured ends of the cable were mostly worn to a tapered end with no discernable fracture features, consistent with ductile overstress fracture. Review of the maintenance logs revealed that the last inspection of the flight controls was completed on November 23, 2021, about 8 months before the accident, at an airplane total time of 40,516.8 hours. An entry on January 5, 2022, and airplane total time 40,536.6 hours, notated that “the left hand rudder stuck pulley at the aft baggage bulkhead” as well as “corrosion of the L/H rudder cable at aft baggage bulkhead.” The mechanic’s response to the entry stated, “upon further inspection, determined cable not corroded. . . No defects.” The airplane had accrued 40,885 total hours at the time of the accident. ## Aircraft - Registration: [N6908M](https://openairdocs.org/aircraft/N6908M), registered now, S/N 20700672, built 1980 (OpenAirDocs) - Reported make and model: CESSNA 207 (A) - Registry model: [Cessna 207A](https://openairdocs.org/model/cessna-207a) (registry code 2073605) (OpenAirDocs) - Registry engine: [Continental IO-520-F](https://openairdocs.org/engine/continental-io-520-f) (registry code 17237, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 20700672 - Year built: 1980 - Airframe hours: 40885 - Engines: CONT MOTOR IO-520-F 300 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Grant Aviation Inc - Registered owner: Grant Aviation Inc - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, July 19, 2022 - Departed: ANW, New Stuyahok, AK - Destination: Same as departure - Flight plan: Company VFR - Airport: DLG, Dilingham, runway 01, 6,400 × 150 ft, asphalt - Equipment: Stall warning system, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 30; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review March 7, 2022; seat: left; flight hours: 1,240 total, 316 in this make and model, 1,100 as pilot in command, 150 in the last 90 days, 35 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 10° at 10 knots, gusting 14 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 68 °F, dew point 43 °F - Altimeter: 30.19 inHg - Icing: Unknown - Observed at: ADL - METAR: PADL 280056Z 01010G14KT 10SM CLR 20/06 A3019 RMK AO2 SLP224 T02000056 ## 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 20220727007549A](https://openairdocs.org/incident/20220727007549A), Jul 27, 2022: Cessna 207A, Dillingham, AK, Minor damage. During landing approach the left rudder pedal was not responsive. The pilot used rudder trim and power to land safely on runway 01 in Dillingham. Rudder… ## Docket (5 files) The files NTSB released with the investigation on January 4, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105670. 6.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14904835&FileExtension=pdf&FileName=ERA22LA358%206120%20Signed_Redacted-Rel.pdf - Memorandum of record - FAA inspector correspondence (item 2, PDF, 2 pages, 513 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14905340&FileExtension=pdf&FileName=MOR%20FAA%20Inspector_Redacted-Rel.pdf - Investigative photographs (item 3, PDF, 4 pages, 709 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14906372&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf - Materials laboratory factual report 22-087 (item 4, PDF, 8 pages, 12 photos, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14846922&FileExtension=pdf&FileName=22-097-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 5, PDF, 2 pages, 207 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14946962&FileExtension=pdf&FileName=ERA22LA358%20Final%20Wreckage%20Release%20Package_Redacted-Rel.pdf 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.