# NTSB CEN12LA299: Piper PA-24-250, N7171P, Shawnee, OK, May 14, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 14, 2012, 13:30 local (18:30 UTC) - Place: Shawnee, OK - Coordinates: 35.357223, -96.943336 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.3572&lon=-96.9433&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report July 18, 2012 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 83645 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12LA299 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83645/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83645 - Page: https://openairdocs.org/ntsb/CEN12LA299 ## Probable cause The improper installation of the mixture cable by maintenance personnel, which allowed the mixture cable to entangle with the landing gear during gear extension and led to the subsequent loss of engine power. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine controls: mixture control](https://openairdocs.org/ntsb-findings/01057602): Aircraft › Aircraft power plant · Incorrect service/maintenance (probable cause); cases with it: [Piper PA-24-250, 1 case](https://openairdocs.org/ntsb-findings/01057602/cases.md?model=7102404), [All aircraft, 41 cases](https://openairdocs.org/ntsb-findings/01057602/cases.md) - [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Piper PA-24-250, 2 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=7102404), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Piper PA-24-250, 4 cases](https://openairdocs.org/ntsb-events/040/sequence.md?model=7102404), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Piper PA-24-250, 8 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=7102404), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing-flare/touchdown: Landing gear not configured](https://openairdocs.org/ntsb-events/095); cases with it: [Piper PA-24-250, 13 cases](https://openairdocs.org/ntsb-events/095/sequence.md?model=7102404), [All aircraft, 584 cases](https://openairdocs.org/ntsb-events/095/sequence.md) ## Analysis The pilot was conducting the second leg of the airplane’s first flight after a recent engine overhaul. On final approach, the pilot lowered the landing gear handle; however, he did not receive confirmation that the landing gear was down. The pilot stated that he applied a lot of force to conduct the manual gear override but that he was not able to get the handle up. Shortly thereafter, the engine lost power. The airplane was substantially damaged during the subsequent forced landing. A postaccident examination of the airplane revealed that the mixture cable was bent, the cable was pulled from its last clamp prior to the carburetor mixture control, and the mixture control was pulled into the cutoff position. The routing of the mixture cable did not match assembly drawings, and several clamps used to route the mixture cable were missing. A grease fitting on the over-center link for the nose landing gear was in line with the bend in the mixture cable. Most likely, the landing gear center link became entangled in the mixture control cable, which prevented the nose landing gear from extending. The mixture likely came to idle when the pilot used extra force to try to extend the landing gear. The mixture cable was not installed properly during the recent engine overhaul. ## Factual narrative On May 14, 2012, approximately 1330 central daylight time, a Piper PA-24-250 airplane, N7171P, was substantially damaged during a forced landing to a field near Shawnee, Oklahoma. The private pilot was not injured. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a ferry flight. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The flight originated from Sundance Airpark (KHSD), Oklahoma City, Oklahoma, approximately 1315, and was en route to Shawnee Regional Airport (KSNL), Shawnee, Oklahoma. On final approach, the pilot lowered the landing gear handle; however, he did not receive confirmation that the landing gear was down and locked. The pilot stated that "a lot of force" was required to conduct the manual gear override, but he was not able to get the handle up. Shortly thereafter, the engine lost power. The pilot performed a gear up, forced landing to a field. During the landing, the right wing was buckled and the firewall was wrinkled. According to the Federal Aviation Administration inspector who traveled to the scene, the mixture cable was bent and would not move. The routing of the mixture cable did not match assembly drawings. The mixture cable was found separated from its last clamp prior to the carburetor mixture control and the mixture control was found in the cutoff position. He also noted that several clamps normally used to route the mixture cable were not present. A grease fitting on the over center link for the nose landing gear was in line with the bend in the mixture cable. According to the pilot, the engine had just been removed and reinstalled for an engine overhaul. ## Aircraft - Registration: [N7171P](https://openairdocs.org/deregistered/N7171P-2018-02-23), registration cancelled 2018-02-23, S/N 24-2339, built 1961 (OpenAirDocs) - Reported make and model: PIPER PA-24-250 - Registry model: [Piper PA-24-250](https://openairdocs.org/model/piper-pa-24-250) (registry code 7102404) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 24-2339 - Airframe hours: 5222 - Engines: LYCOMING O-540 SERIES 250 horsepower reciprocating - Damage: Substantial damage - Flight: Ferry, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 25, 2011 - Departed: KHSD, Oklahoma City, OK - Destination: KSNL, Shawnee, OK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review November 28, 2010; seat: left; flight hours: 1,156 total, 356 in this make and model, 1,004 as pilot in command, 1 in the last 90 days, 1 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 54 °F - Altimeter: 30.15 inHg - Observed at: KSNL, 1 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 20120514012489A](https://openairdocs.org/incident/20120514012489A), May 14, 2012: Piper PA-24-250, Shawnee, OK, Substantial damage. The event occurred as follows from statements and collected data. The Piper comanche 250 N7171P [privacy data omitted] departed form pwa (wiley post) at just… ## Docket (4 files) The files NTSB released with the investigation on June 5, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83645. 3.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40368648&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Telephone Conversation - CEN12LA299 - Evans (FAA) (item 2, .PDF, 48 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40368651&FileExtension=.PDF&FileName=Record%20of%20Telephone%20Conversation%20-%20CEN12LA299%20-%20Evans%20(FAA)-Master.PDF - Photograph 01 - Mixture Cable at the Engine (provided by the FAA) (item 3, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40368649&FileExtension=.PDF&FileName=Photograph%2001%20-%20Mixture%20Cable%20at%20the%20Engine%20(provided%20by%20the%20FAA)-Master.PDF - Photograph 02 - Bend in the Mixture Cable (Provided by the FAA) (item 4, .PDF, 45 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40368650&FileExtension=.PDF&FileName=Photograph%2002%20-%20Bend%20in%20the%20Mixture%20Cable%20(Provided%20by%20the%20FAA)-Master.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.