# NTSB WPR13LA035: Cessna 172M, N21391, Modesto, CA, November 6, 2012 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: November 6, 2012, 11:00 local (19:00 UTC) - Place: Modesto, CA - Coordinates: 37.467777, -121.073608 - Nearby events: https://openairdocs.org/map.md?lat=37.4678&lon=-121.0736&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report April 10, 2013 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Adminstration FSDO - NTSB case key (mKey): 85542 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR13LA035 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/85542/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=85542 - Page: https://openairdocs.org/ntsb/WPR13LA035 ## Probable cause Failure of the throttle control cable during maneuvering flight, which resulted in a partial loss of engine power. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine controls: power lever](https://openairdocs.org/ntsb-findings/01057603): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Cessna 172M, 2 cases](https://openairdocs.org/ntsb-findings/01057603/cases.md?model=2072418), [All aircraft, 95 cases](https://openairdocs.org/ntsb-findings/01057603/cases.md) - [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Not specified; cases with it: [Cessna 172M, 1 case](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=2072418), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Cessna 172M, 3 cases](https://openairdocs.org/ntsb-events/340/sequence.md?model=2072418), [All aircraft, 821 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Cessna 172M, 16 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2072418), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 172M, 100 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2072418), [All aircraft, 10,154 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis During a photography mission, the pilot applied full engine power, and the engine speed dropped to idle. After attempting a series of troubleshooting steps, the engine did not respond, and the pilot performed a forced landing into a field. The airplane landed hard and nosed over. Postaccident examination of the engine revealed that the outer jacket of the throttle control cable had fragmented at the carburetor attach point, exposing the inner cable. Subsequent throttle control movement resulted in the cable flexing out of the jacket, rather than moving the throttle control arm at the carburetor. No life limit existed for the cable, which was most likely installed at the time of airframe manufacture, 38 years prior to the accident. Further examination of the engine revealed no additional evidence of a mechanical malfunction or failure that would have precluded normal operation. ## Factual narrative HISTORY OF FLIGHT On November 6, 2012, about 1100 Pacific standard time, a Cessna 172M, N21391, landed hard during a forced landing near Modesto, California. The private pilot was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91, as an aerial photography flight. The pilot and photographer/passenger sustained minor injuries; the airplane sustained substantial damage. The local flight departed Modesto City-County Airport-Harry Sham Field, Modesto, at 1042. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot and passenger departed with the intention of taking photographs of fields in the Patterson area. Having reached their destination, and after completing the first round of photographs, the passenger requested that the airplane's airspeed be reduced. While at an altitude of 1,200 feet agl, the pilot reduced the engine speed to 1,700 rpm, applied carburetor heat, 10 degrees of flaps, and reduced the airspeed to 80 knots. She then periodically increased the engine speed to confirm its operation. After about 10 minutes, the photographer requested that they climb to a higher altitude. The pilot applied forward throttle control, but the engine speed subsequently dropped to idle. After attempting a series of troubleshooting steps, the engine did not respond, and with the airplane descending, the pilot performed a forced landing into a field. The airplane landed hard and nosed over, sustaining substantial damage to the firewall, vertical stabilizer, and both wings. TESTS AND RESEARCH An inspector from the Federal Aviation Administration (FAA) examined the airplane subsequent to recovery. The nose landing gear assembly had become separated from the firewall during the accident sequence. The engine remained attached to the firewall by its mount, which sustained minimal damage. The carburetor remained attached to the inlet manifold; the inlet air filter and heat box sustained crush damage. Examination of the throttle control system revealed that the plastic outer jacket of the throttle cable had fragmented between the attach bracket and the carburetor throttle control arm. The inner armor and control cables were exposed, and movement of the cabin throttle control resulted in the cable flexing out of the jacket, rather than moving the control arm. Further examination did not reveal any anomalies with the airframe or engine that would have precluded normal operation. Refer to the engine and airframe report included in the public docket for further details. Engine maintenance records revealed that the airplane had undergone a 100-hour inspection on November 4, 2012. At that time, the airframe had accrued a total of 3,240 flight hours. There were no logbook entries indicating the throttle control cable had been replaced since the airplane's manufacture in 1974. ADDITIONAL INFORMATION A review of the FAA Service Difficulty Report database for the Cessna 172 series revealed one similarfailure of the throttle cable sheathing. This failure occurred in a 172M airplane, and the cable had accrued 3,857 flight hours. No FAA airworthiness directives or Cessna service bulletins existed for such a failure, and the cable had no life limit. ## Aircraft - Registration: [N21391](https://openairdocs.org/deregistered/N21391-2015-05-13), registration cancelled 2015-05-13, S/N 17263943, built 1974 (OpenAirDocs) - Reported make and model: CESSNA 172M - Registry model: [Cessna 172M](https://openairdocs.org/model/cessna-172m) (registry code 2072418) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17263943 - Airframe hours: 3240 - Engines: LYCOMING O-320 SERIES 180 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial observation, Part 91 - Airworthiness certificate: Standard, Normal; Standard, Utility - Last inspection: 100 hour, November 4, 2012, 4 hours before - Departed: KMOD, Modesto, CA - Destination: KMOD, Modesto, CA - Airport: MOD, Modesto ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 67; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review April 26, 2011; seat: left; flight hours: 524 total, 349 in this make and model, 429 as pilot in command, 5 in the last 90 days, 2 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 6 statute miles - Lowest ceiling: none - Temperature: 72 °F, dew point 54 °F - Altimeter: 30.07 inHg - Observed at: KMOD, 12 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 20121106024669A](https://openairdocs.org/incident/20121106024669A), Nov 6, 2012: Cessna 172M, Patterson, CA, Substantial damage. On November 6, 2012 at approximately 1842 UTC, N21391, a Cessna 172, depart the modesto city airport (kmod) with two people on board. The aircraft was piloted… ## Docket (3 files) The files NTSB released with the investigation on February 14, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=85542. 2.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 404 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40385738&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - FAA Report (item 2, .PDF, 21 photos, 2.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40385739&FileExtension=.PDF&FileName=FAA%20Report-Redacted.PDF - Throttle Cable Service Difficulty Report (item 3, .TXT, 160 B): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40385740&FileExtension=.txt&FileName=Throttle%20Cable%20Service%20Difficulty%20Report-Master.txt 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.