# NTSB CEN17LA070: Aeronca 15AC, N1337H, Pontiac, MI, December 23, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 23, 2016, 16:18 local (21:18 UTC) - Place: Pontiac, MI - Coordinates: 42.665554, -83.420555 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.6656&lon=-83.4206&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report April 20, 2020 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration, East Michigan - NTSB case key (mKey): 94570 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN17LA070 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94570/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94570 - Page: https://openairdocs.org/ntsb/CEN17LA070 ## Probable cause The improper installation of the left wheel brake torque plate by maintenance personnel, which resulted in the separation of the torque plate from the axle endplate and a loss of directional control during landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: brake](https://openairdocs.org/ntsb-findings/01023242): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Aeronca 15AC, 3 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md?model=0191202), [All aircraft, 297 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md) - [Landing gear system: brake](https://openairdocs.org/ntsb-findings/01023242): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Aeronca 15AC, 3 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md?model=0191202), [All aircraft, 297 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md) - [Maintenance: modification/alteration](https://openairdocs.org/ntsb-findings/02062030): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Aeronca 15AC, 1 case](https://openairdocs.org/ntsb-findings/02062030/cases.md?model=0191202), [All aircraft, 69 cases](https://openairdocs.org/ntsb-findings/02062030/cases.md) - [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Aeronca 15AC, 1 case](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=0191202), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Aeronca 15AC, 2 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=0191202), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Aeronca 15AC, 2 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=0191202), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) - [Object/animal/substance: snow/ice](https://openairdocs.org/ntsb-findings/03022060): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Aeronca 15AC, 1 case](https://openairdocs.org/ntsb-findings/03022060/cases.md?model=0191202), [All aircraft, 67 cases](https://openairdocs.org/ntsb-findings/03022060/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: [Aeronca 15AC, 1 case](https://openairdocs.org/ntsb-events/040/sequence.md?model=0191202), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Aeronca 15AC, 1 case](https://openairdocs.org/ntsb-events/330/sequence.md?model=0191202), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Aeronca 15AC, 2 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=0191202), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Aeronca 15AC, 3 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0191202), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Aeronca 15AC, 2 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=0191202), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The private pilot was concluding a local flight in the tailwheel-equipped airplane. After numerous uneventful touch-and-go landings, the pilot attempted a full-stop landing when the airplane suddenly swerved to the left shortly after touchdown. The pilot attempted to regain directional control by applying right rudder and increasing engine power for an aborted landing; however, the airplane swerved to the right and collided with a snowbank next to the runway. The airplane sustained substantial damage to both main wing spars and the rudder. A postaccident examination revealed that the left wheel brake torque plate had separated from the landing gear axle endplate, which allowed the brake assembly to rotate with the brake disk that was attached to the wheel. The airplane had been modified with Cleveland wheels and brakes through a supplemental type certificate (STC). However, additional examination of the brake torque plates revealed that they had not been installed in accordance with the STC installation instructions. Specifically, the torque plates were not modified with two 0.25-inch holes that were required to ensure proper alignment with the landing gear axle endplate, and improperly sized bushings had been used during the installation. The improper torque plate installation allowed for movement of the torque plate and unintended transverse loading of the anchor bolts, which resulted in the fracture of the anchor bolts that secured the left brake torque plate to the axle endplate. The failure of the left brake likely caused the loss of directional control during landing. ## Factual narrative On December 23, 2016, about 1618 eastern standard time, an Aeronca model 15AC airplane, N1337H, collided with a snowbank and nosed over while landing at Oakland County International Airport (PTK), Pontiac, Michigan. The private pilot was not injured, and the airplane sustained substantial damage. The airplane was registered to Samcran LLC and operated under the provisions of Title 14 Code of Federal Regulations Part 91 without a flight plan. Day visual meteorological conditions prevailed for the local flight that departed PTK about 1500.The pilot reported that the purpose of the flight was to practice landings in the tailwheel-equipped airplane. After departure, he remained in the airport traffic pattern and completed 14 uneventful touch-and-go landings before deciding to conclude the flight with a full stop landing on runway 27R. He reported that he made an uneventful full stall (three point) landing on the runway centerline. However, shortly after touchdown, the airplane suddenly swerved to the left. He attempted to regain directional control with an application of right rudder and increased engine power for an aborted landing. The airplane then swerved to the right as he simultaneously applied forward stick pressure to get the tail airborne. The airplane continued to swerve right until it collided with a 3 ft high snowbank located alongside the runway. The airplane then nosed over and came to rest in the snow-covered area located off the right side of the runway. The pilot was able to exit the airplane uninjured after releasing his lap belt. The pilot had accumulated 205 hours in the airplane since he purchased it in May 2015. The pilot noted that most of his flight experience in the airplane, 172.9 hours, had been flown with the airplane equipped with landing floats instead of a conventional (tailwheel) landing gear. He had logged 32.1 hours of tailwheel time, all of which were flown in the accident airplane. The pilot received his tailwheel endorsement on March 11, 2016. A postaccident examination by a Federal Aviation Administration (FAA) airworthiness inspector revealed substantial damage to both main wing spars and the rudder. The FAA inspector reported that the four 0.25 inch anchor bolts used to attach the left brake torque plate to its respective landing gear axle endplate had sheared. The unrestrained torque plate allowed the brake assembly to rotate with the brake disk that was attached to the wheel. With the forward rotation, the brake line was pulled around the gear leg until the 90° aluminum fitting that connected the brake line to the caliper assembly sheared. The tire inner sidewall exhibited a gash that partially exposed the inner tube. The inner tube did not rupture but was partially protruding from the gash in the tire sidewall. The sheared anchor bolts had worn a grove on the inboard surface of the left brake disk. According to maintenance documentation, on January 27, 2016, the airplane had been modified through theimplementation of STC No. SA1114NW with Cleveland 8.00 x 6.00 main wheels, tires, and 6 inch external, single cylinder, dual piston brake assemblies. The landing floats were reinstalled on an unknown date during 2016. On December 17, 2016, the landing floats were removed, and the main landing gear and wheels were reinstalled to convert the airplane back into a conventional gear land airplane. The accident occurred during the second flight after the airplane was reequipped with the conventional landing gear. The installation instructions for STC No. SA1114NW specified that the stock Cleveland brake torque plates be modified per the accompanying installation drawing No. 1200-4 and to use 0.375 inch outside diameter (OD) to 0.25 inch inside diameter (ID) bushings. Installation drawing No. 1200-4 specified that each torque plate required two 0.25 inch holes to be marked and drilled to ensure proper alignment with their respective landing gear axle endplate. Each torque plate was then attached to its respective landing gear axle endplate with four 0.25 inch anchor bolts and washers. The two 0.25 inch holes drilled in each torque plate did not require bushings when installed with a 0.25 inch anchor bolt; however, the remaining two 0.375 inch holes used to attach each torque plate required 0.375 inch OD to 0.25 inch ID bushings to properly support the 0.25 inch anchor bolts. Further examination of the airplane revealed that both torque plates were not modified and installed in accordance with the STC No. SA1114NW installation instructions. Specifically, the supplied brake torque plates were not modified with the two additional 0.25 inch holes to ensure proper alignment with the landing gear axle endplate. Additionally, both torque plates were installed with improperly sized bushings in multiple holes. The left torque plate, which had separated from the left landing gear axle endplate, had two bushing remaining; one bushing had the correct 0.25 inch ID, the other bushing had a larger 0.3125 inch ID. The right torque plate, which remained attached to the right landing gear axle endplate, was incorrectly installed with four 0.3125 inch ID bushings. ## Aircraft - Registration: [N1337H](https://openairdocs.org/deregistered/N1337H-2026-08-24), registration cancelled 2026-08-24, S/N 15AC-377, built 1949 (OpenAirDocs) - Reported make and model: AERONCA 15AC - Registry model: [Aeronca 15AC](https://openairdocs.org/model/aeronca-15ac) (registry code 0191202) (OpenAirDocs) - Registry engine: [Continental C145 series](https://openairdocs.org/engine/continental-c145-series) (registry code 17012, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 15AC-377 - Year built: 1949 - Airframe hours: 4380 - Engines: Continental C-145-2 145 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 14, 2016 - Departed: PTK, Pontiac, MI - Destination: PTK, Pontiac, MI - Airport: PTK, Oakland County International A, runway 27R, 5,676 × 100 ft, asphalt - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; injuries: none; private; airplane ratings: single-engine land, single-engine sea; medical: class 3, with waivers/limitations; last flight review October 30, 2016; seat: left; restraint: lap only; flight hours: 342 total, 205 in this make and model, 253 as pilot in command, 49 in the last 90 days, 16 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 6 knots - Visibility: 5 statute miles - Lowest ceiling: 8,000 ft broken - Temperature: 34 °F, dew point 28 °F - Altimeter: 30.18 inHg - Observed at: PTK ## 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 20161223022369A](https://openairdocs.org/incident/20161223022369A), Dec 23, 2016: Aeronca 15AC, Waterford, MI, Substantial damage. Left brake locked/failed on touchdown (conventional gear acft) causing the aircraft to immediately veer left. Pilot attempted go around by adding power and… ## Docket (7 files) The files NTSB released with the investigation on November 8, 2019, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94570. 5.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40477886&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Memorandum of Conversation (Cranston Jones) (item 2, .PDF, 90 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40477887&FileExtension=.PDF&FileName=Memorandum%20of%20Conversation%20(Cranston%20Jones)-Master.PDF - Memorandum of Conversation (Richard Anderson) (item 3, .PDF, 85 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40477888&FileExtension=.PDF&FileName=Memorandum%20of%20Conversation%20(Richard%20Anderson)-Master.PDF - Email Correspondence (Richard Anderson) (item 4, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40477892&FileExtension=.PDF&FileName=Email%20Correspondence%20(Richard%20Anderson)-Master.PDF - Installation Instructions and Drawing (STC SA1114NW) (item 5, .PDF, 886 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40477893&FileExtension=.PDF&FileName=Installation%20Instructions%20and%20Drawing%20(STC%20SA1114NW)-Master.PDF - Airframe Logbook (Excerpts) (item 6, .PDF, 429 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40477894&FileExtension=.PDF&FileName=Airframe%20Logbook%20(Excerpts)-Master.PDF - Photos (item 7, .PDF, 3 photos, 915 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40477895&FileExtension=.PDF&FileName=Photos-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.