# NTSB GAA17CA093: Piper PA 34, N2844T, Denton, TX, December 7, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: December 7, 2016, 11:45 local (17:45 UTC) - Place: Denton, TX - Coordinates: 33.20222, -97.198059 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.2022&lon=-97.1981&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining event: [Taxi-from runway: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report July 20, 2017 - Report: Approved by Office Director - NTSB office: General Aviation Accidents - Parties: FAA - NTSB case key (mKey): 94495 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA17CA093 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94495/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94495 - Page: https://openairdocs.org/ntsb/GAA17CA093 ## Probable cause The flight instructor’s decision to continue to taxi the airplane to the parking area with a known brake malfunction, which resulted in a loss of directional control and subsequent impact with a parked airplane. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Instructor/check pilot (probable cause); cases with it: [Piper PA-34-200, 2 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=7103405), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Landing gear system: brake](https://openairdocs.org/ntsb-findings/01023242): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Piper PA-34-200, 2 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md?model=7103405), [All aircraft, 297 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md) - [Object/animal/substance: aircraft](https://openairdocs.org/ntsb-findings/03022040): Environmental issues › Physical environment · Effect on operation; cases with it: [Piper PA-34-200, 1 case](https://openairdocs.org/ntsb-findings/03022040/cases.md?model=7103405), [All aircraft, 116 cases](https://openairdocs.org/ntsb-findings/03022040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Taxi-from runway: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Piper PA-34-200, 4 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=7103405), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Taxi-from runway: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Piper PA-34-200, 10 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7103405), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis According to the flight instructor in the multiengine airplane, he occupied the right seat during the instructional flight. The flight instructor reported that, during the landing roll, the brakes on his side were inoperative, but the brakes used by the pilot under instruction appeared to function normally. The flight instructor allowed the pilot under instruction to taxi to parking. During the right turn in the parking area, the pilot under instruction was told to apply both brakes, and the airplane started to "pull left." The flight instructor attempted to use differential thrust to arrest the left pull by increasing the right engine speed, but the attempt had no effect. The flight instructor shut down both engines; however, the left wing struck a parked airplane and came to a stop. The airplane sustained substantial damage to the left wing. The flight instructor reported that the accident could have been prevented if he had stopped on the taxiway and not entered the parking ramp. A postaccident examination of the brake assembly revealed that the right brake actuator piston "o" ring had failed, which decreased hydraulic brake pressure and prevented proper brake function of the airplane. ## Factual narrative According to the flight instructor in the multi-engine airplane, he occupied the right seat during the instructional flight. The flight instructor reported that during the landing roll, the brakes on his side were inoperative, but the brakes used by the pilot under instruction appeared to function normally. The flight instructor allowed the pilot under instruction to taxi to parking. During the right turn in the parking area, the pilot under instruction was told to apply both brakes, and the airplane started to "pull left". The flight instructor attempted to use differential thrust to arrest the left pull by increasing the right engine speed, but the attempt had no effect. The flight instructor shut down both engines, however, the multi-engine airplane's left wing struck a parked single-engine airplane and came to a stop. The multi-engine airplane sustained substantial damage to the left wing. The flight instructor reported that the accident could have been prevented if he would have stopped on the taxiway and not entered the parking ramp. The brake assembly was examined to determine the scope of pre-accident mechanical malfunctions or failures with the airplane's brake system, that would have precluded normal operation. It was determined that the right side brake actuator piston "o" ring failed, which decreased hydraulic brake pressure, preventing proper brake function of the airplane. ## Aircraft - Registration: [N2844T](https://openairdocs.org/deregistered/N2844T-2017-12-22), registration cancelled 2017-12-22, S/N 34-7250174, built 1972 (OpenAirDocs) - Reported make and model: PIPER PA 34 (200) - Registry model: [Piper PA-34-200](https://openairdocs.org/model/piper-pa-34-200) (registry code 7103405) (OpenAirDocs) - Registry engine: [Lycoming I0360 series](https://openairdocs.org/engine/lycoming-i0360-series) (registry code 41515, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 34-7250174 - Year built: 1972 - Airframe hours: 10733.6 - Engines: LYCOMING LIO-360 200 horsepower reciprocating; LYCOMING IO-360-CEI6 200 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: U S Aviation Group LLC - Registered owner: U S Aviation Group LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, October 17, 2016 - Departed: KDTO, Denton, TX - Destination: KDTO, Denton, TX - Flight plan: VFR - Airport: DTO, Denton Enterprise, runway 36, 7,002 × 150 ft, asphalt - Equipment: Stall warning system, Electronic primary flight display, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 24; injuries: none; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review February 26, 2016; seat: right; restraint: 3-point; flight hours: 657.4 total, 248.5 in this make and model, 585 as pilot in command, 204.1 in the last 90 days, 51.2 in the last 30 days - Student pilot; age 23; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review July 22, 2016; seat: left; restraint: 3-point; flight hours: 227.8 total, 13.1 in this make and model, 124.6 as pilot in command, 13.1 in the last 90 days, 5 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 48 °F, dew point 39 °F - Altimeter: 30.11 inHg - Observed at: DTO ## 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 20161207024701A](https://openairdocs.org/incident/20161207024701A), Dec 7, 2016: Piper PA-34-200, Denton, TX, Substantial damage. On December 7, 2016, at 1230 CST, a Piper PA-34-200, N2844T, s/n 34-7250174, owned by us aviation group LLC, 4850 spartan dr., Denton, TX 76207, following a… ## Docket (3 files) The files NTSB released with the investigation on June 21, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94495. 3.9 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453564&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Brake Examination (item 2, .PDF, 73 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453565&FileExtension=.PDF&FileName=Brake%20Examination-Master.PDF - Photos (Courtesy of FAA) (item 3, .PDF, 2 photos, 158 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453566&FileExtension=.PDF&FileName=Photos%20(Courtesy%20of%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.