# NTSB SEA03LA066: Maule MX-7-235, N114MK, Plummer, ID, April 20, 2003 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 19, 2003, 17:15 local (Apr 20, 2003, 00:15 UTC) - Place: Plummer, ID - Coordinates: 47.343334, -116.915 - Nearby events: https://openairdocs.org/map.md?lat=47.3433&lon=-116.9150&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report July 23, 2003 - Report: Approved by Office Director - Parties: Spokane FSDO - NTSB case key (mKey): 56860 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA03LA066 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/56860/pdf - Page: https://openairdocs.org/ntsb/SEA03LA066 ## Probable cause The jamming of the left parking brake locking tab on a burr on the left brake master cylinder activation rod during the landing roll, resulting in the left brake becoming locked in a position where excessive braking was applied. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, landing - roll - landing gear,parking brake - jammed (cause) - Nose over, landing - roll - landing gear,normal brake system - locked (cause) ## Analysis During the last part of the landing roll, as the pilot was applying the brakes, the left main gear brake locked up, resulting in the tailwheel-equipped aircraft pulling hard to the left. As he tried to bring the aircraft to a stop, it nosed over onto its back. It was ultimately determined that the parking brake lock activation tab on the left brake master cylinder became stuck on the master cylinder plunger rod, resulting in a situation where the pilot was unable to reduce braking pressure on the left side. A further inspection of the system revealed that there was a burr on the master cylinder shaft. When the left brake was applied and then released, the burr lifted the parking brake locking tab, through which the cylinder shaft passes, and the spring that should press the tab back down to the unlocked position was unable to do so. This resulted in the failure of the brake to release, and it therefore remained locked in whatever had been its most fully-applied position. The malfunction was able to be duplicated during a post-accident inspection/test of the system. ## Factual narrative On April 19, 2003, approximately 1715 Pacific daylight time, a Maule MX-7-235, N114MK, nosed over during the landing roll at a private grass airstrip near Plummer, Idaho. The commercial pilot and his passenger were not injured, but the aircraft, which is owned and operated by the pilot, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which departed Saint Maries, Idaho, about 15 minutes earlier, was being operated in visual meteorological conditions. No flight plan was filed. There was no report of an ELT activation. According to the pilot, during the last part of the landing roll, as he was applying the brakes, the left main gear brake locked up, resulting in the tailwheel-equipped aircraft pulling hard to the left. As he tried to bring the aircraft to a stop, it nosed over onto its back. According to the FAA Airworthiness Inspector who responded to the accident site, the parking brake lock activation tab on the left brake master cylinder became stuck on the master cylinder plunger rod, resulting in a situation where the pilot was unable to reduce braking pressure on the left side. A further inspection of the system revealed that there was a burr on the master cylinder shaft. When the left brake was applied and then released, the burr lifted the parking brake locking tab, through which the cylinder shaft passes, and the spring that should press the tab back down to the unlocked position was unable to do so. This resulted in the failure of the brake to release, and it therefore remained locked in whatever had been its most fully-applied position. The FAA Airworthiness Inspector who examined the system after the accident was able to duplicate the malfunction during his inspection (see attached FAA report). ## Aircraft - Registration: [N114MK](https://openairdocs.org/aircraft/N114MK), registered now, S/N 10022-C (OpenAirDocs) - Reported make and model: Maule MX-7-235 - Registry model: [Maule MX-7-235](https://openairdocs.org/model/maule-mx-7-235) (registry code 5470207) (OpenAirDocs) - Registry engine: [Lycoming IO-540 series](https://openairdocs.org/engine/lycoming-io-540-series) (registry code 41530, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 10022C - Airframe hours: 1166 - Engines: Lycoming IO-540-W1A5D 235 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Kevin G. Griffin - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 3, 2002, 49 hours before - Departed: S72, Saint Maries, ID - Destination: Plummer, ID - Airport: runway 27, 1,500 × 150 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 30; injuries: none; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; last flight review January 8, 2003; seat: left; flight hours: 1,306 total, 934 in this make and model, 1,238 as pilot in command, 9 in the last 90 days, 6 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 61 °F - Altimeter: 30.12 inHg ## 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 20030420005249A](https://openairdocs.org/incident/20030420005249A), Apr 20, 2003: Maule MX7235, Plummer, ID, Substantial damage. (-23) On 4/20/03 pilot took off from auburn, WA and landed at tekoa, WA. He was picked up by relatives and went to their farm to check the condition of the… ## Other investigations on N114MK (1) 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 WPR12LA207](https://openairdocs.org/ntsb/WPR12LA207), May 11, 2012: Maule MX-7 (N114MK), Roche Harbor, WA, substantial damage. Probable cause: A damaged brake master cylinder piston rod, which resulted in a landing with the left brake applied. The damage was a result of normal parking brake operation. 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.