# NTSB MIA02LA138: Maule MXT-7-180A, N10550, Trenton, GA, July 23, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 23, 2002, 17:00 local (21:00 UTC) - Place: Trenton, GA - Coordinates: 34.904724, -85.459724 - Nearby events: https://openairdocs.org/map.md?lat=34.9047&lon=-85.4597&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report April 23, 2003 - Report: Approved by Office Director - Parties: FSDO FAA - NTSB case key (mKey): 55288 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA02LA138 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55288/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=55288 - Page: https://openairdocs.org/ntsb/MIA02LA138 ## Probable cause The failure of the pilot to clear the engine during a prolonged approach at idle power resulting in the engine hesitating during application of power to arrest the descent for landing touchdown resulting in a hard landing and separation of the left main landing gear wheel. Contributing to the accident was incomplete fusion of the weld joint between the left main landing gear axle and wheel spacer and the lower than normal idle setting of the engine. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Hard landing, landing - flare/touchdown - landing gear,axle - improper/poor weld (cause) - maintenance,adjustment - improper, other maintenance personnel (cause) - fuel system,carburetor - underspeed - throttle/power control - improper use of, pilot in command (cause) - engine assembly - output low - landing gear,axle - overload - On ground/water encounter with terrain/water, landing - terrain condition - grass ## Analysis According to the pilot, he had to clear a ridgeline on his approach path to a 2,000 foot grass strip, necessitating a short field approach that was steep, using idle power. When he rapidly applied power in the flare, the engine hesitated, and the touchdown was firm. The left main wheel fractured at the weld joint between the axle and the hub spacer , causing the wheel to separate, the left landing strut to dig into the sod, and the aircraft to ground loop. The ground loop resulted in a collapsed nose gear strut and a propeller strike. Postcrash examination of the engine revealed metal shavings contamination in the gascolator. Postcrash run of the engine revealed an idle rpm of less than 500 rpm. The normal idle rpm range should be 600 to 800 rpm. The left main wheel/axle was sent to the NTSB Materials Laboratory for analysis of the fracture. The examination showed the axle to spacer weld had only achieved about 30 percent fusion of the surface at the end of the axle. The remaining fracture surface was consistent with overstress separation. ## Factual narrative On July 23, 2002, about 1700 eastern daylight time, a Maule MXT-7-180A , N10550, registered to Wellfound Air Inc., operated by a private individual as a Title 14 CFR Part 91 personal flight, crashed while landing at the Lookout Mountain Ultralight Airport, near Trenton, Georgia. Visual meteorological conditions prevailed and no flight plan was filed. The airplane received substantial damage, and the private-rated pilot, the sole occupant aboard, was not injured. The flight departed the Cobb County-McCollum Field Airport near Marietta, Georgia, about 50 minutes before the accident. The pilot stated that during his short field approach to a 2,000-foot grass strip, the engine was slow to respond to his throttle advancement during his landing flare and the airplane landed hard. The pilot stated that the left axle broke, the left landing gear strut dug into the ground, and during the subsequent ground loop, the nose gear collapsed, the propeller struck the ground, and the airframe sustained some twisting deformation. On August 8, 2002, the aircraft's left wheel axle assembly, consisting of a steel tube of 1.5-inch length and .12-inch wall thickness welded to a 3-inch diameter low carbon steel hub spacer, was shipped to the NTSB Materials Laboratory, Washington, DC, for failure mode examination. According to the Laboratory Report, "Visual and optical microscopic examination of the fracture surfaces revealed that the welding process had achieved incomplete fusion with the axle." The portion of the weld between the axle and hub spacer that exhibited proper fusion, (about 30-per cent of the total weldment) revealed overstress fracture. There was no evidence of fatigue, and the corrosion that was observed on the fracture surfaces occurred after the parts were separated during the hard landing. The Materials Laboratory Report is an attachment to this report. On September 17, 2002, during a telephone call to the NTSB, the pilot confirmed that fuel system repairs had been recently performed on the aircraft. Due to a fuel leak in the left wing, the left wing fuel tank had been removed and the left fuel strainer had been replaced. Additionally, the fuel selector valve had been replaced. On October 8, 2002, during a subsequent telephone call to the NTSB, the pilot stated that, if the aircraft's engine had a low idle condition, that the low idle combined with the use of carburetor heat, may have led to the power hesitation he experienced. He mentioned this had been a theory of his all along. He could not recall any recent adjustment made to the throttle linkage or carburetor. He further stated he could not recall what rpm the engine idled at, only that it idled "OK" during his runup. A data sheet provided by Maule Air, Inc., revealed the minimum idle rpm for the MXT-7-180A should be no less than 600 rpm and no more than 800 rpm. Copies of "Record of Phone Conversation" forms and factory data sheets are attachments to this report. On October 2, 2002, under NTSB oversight, the engine underwent a static test run. Prerun examination by NTSB personnel revealed that the gascolator and its filter screen contained both ferrous and non-ferrous metal shavings of a silver color. The carburetor filter screen was found clean and clear of contaminates. The engine was run using a test propeller and the engine's own electrical and ignition system. The engine started easily and idled for about 2 minutes indicating normal fuel pressure. While insuring that the carburetor linkage adjustment screw was hard against its low speed stop, the idle rpm was less than 500 rpm. When the throttle was jam accelerated from its idle setting, the engine died. When the idle rpm was raised to 700 rpm and carburetor heat was applied, the carburetor easily accepted the jam acceleration. Throttle range of motion was abruptly actioned in both directions with no adverse operation. ## Aircraft - Registration: [N10550](https://openairdocs.org/aircraft/N10550), registered now, S/N 21060C, built 1998 (OpenAirDocs) - Reported make and model: Maule MXT-7-180A - Registry model: [Maule MXT-7-180A](https://openairdocs.org/model/maule-mxt-7-180a) (registry code 5460187) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 21060C - Airframe hours: 1201 - Engines: Lycoming O-360-C4F 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Roderick Henderson - Registered owner: Wellfound Air Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, June 20, 2002, 19 hours before - Departed: RYY, Marietta, GA - Destination: 0GE3, Trenton, GA - Airport: OGE3, Lookout Mountain Flight Park, runway 18, 2,000 × 50 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; last flight review September 25, 2001; seat: left; flight hours: 316 total, 225 in this make and model, 253 as pilot in command, 27 in the last 90 days, 5 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 210° at 4 knots - Visibility: 7 statute miles - Lowest ceiling: 7,000 ft broken - Temperature: 75 °F, dew point 66 °F - Altimeter: 30.07 inHg - Observed at: CHA, 18 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 20020723035799A](https://openairdocs.org/incident/20020723035799A), Jul 23, 2002: Maule MXT7180A, Trenton, GA, Substantial damage. (-23) Mr. Henderson was completing a flight to the Ultralight/flight park (OGE3) located in Trenton, GA in his Maule (MXT-7-180A) aircraft. The field is short… ## Docket (4 files) The files NTSB released with the investigation on March 11, 2003, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=55288. 3.1 MB in all. - Materials Laboratory Factual Report 02-110, Fracture of Left MLG axle assembly (item 1, .PDF, 3 photos, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40172799&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%2002-110,%20Fracture%20of%20Left%20MLG%20axle%20assembly-Master.PDF - NTSB Engine Test Report (item 2, .PDF, 76 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40178120&FileExtension=.PDF&FileName=NTSB%20Engine%20Test%20Report-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 3, .PDF, 371 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40463626&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 4, .PDF, 101 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40463627&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-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.