# NTSB ERA12LA293: Prendergast John/Vans RV-7A, N5025G, Gerrardstown, WV, April 16, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 16, 2012, 15:00 local (19:00 UTC) - Place: Gerrardstown, WV - Coordinates: 39.351665, -78.099723 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.3517&lon=-78.0997&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report January 31, 2013 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 83441 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA12LA293 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83441/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83441 - Page: https://openairdocs.org/ntsb/ERA12LA293 ## Probable cause The pilot/builder's misjudgment of the required spacer width needed after engine housing lap grinding, which resulted in bearing oil hole misalignment and insufficient internal engine lubrication. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Power plant](https://openairdocs.org/ntsb-findings/01057100): Aircraft › Aircraft power plant · Related maintenance info; cases with it: [Prendergast John/Vans RV-7A, 1 case](https://openairdocs.org/ntsb-findings/01057100/cases.md?model=0561984), [All aircraft, 198 cases](https://openairdocs.org/ntsb-findings/01057100/cases.md) - [Fluids: oil](https://openairdocs.org/ntsb-findings/01071020): Aircraft › Fluids/misc hardware · Related maintenance info; cases with it: [Prendergast John/Vans RV-7A, 1 case](https://openairdocs.org/ntsb-findings/01071020/cases.md?model=0561984), [All aircraft, 174 cases](https://openairdocs.org/ntsb-findings/01071020/cases.md) - [Info processing/decision: expectation/assumption](https://openairdocs.org/ntsb-findings/02041525): Personnel issues › Action/decision · Owner/builder (probable cause); cases with it: [Prendergast John/Vans RV-7A, 1 case](https://openairdocs.org/ntsb-findings/02041525/cases.md?model=0561984), [All aircraft, 51 cases](https://openairdocs.org/ntsb-findings/02041525/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Prendergast John/Vans RV-7A, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=0561984), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Prendergast John/Vans RV-7A, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=0561984), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Prendergast John/Vans RV-7A, 2 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=0561984), [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: [Prendergast John/Vans RV-7A, 1 case](https://openairdocs.org/ntsb-events/096/sequence.md?model=0561984), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis According to the pilot, after about 2 1/2 hours of local flight, while maneuvering at 3,000 feet, the airplane's rotary engine coolant temperature rose. As the pilot turned the airplane back toward the departure airport, the engine seized and would not turn over during an attempted restart. The pilot performed a forced landing in a field, and the airplane nosed over. The pilot, who was also the airplane's builder, subsequently disassembled the engine and found that the stationary gear/bearing was frozen to the eccentric shaft. The pilot also reported that he had recently attempted to fine tune the engine by having the side and intermediate housings undergo lap grinding. The pilot knew the grinding would require wider spacers, which he used, but which may have still been insufficient in width. The insufficient width resulted in bearing oil hole misalignment on the eccentric shaft, which blocked oil from reaching the rotating engine and reduction drive shaft parts. ## Factual narrative On April 16, 2012, about 1500 eastern daylight time, an experimental amateur-built Van's Aircraft RV-7A, N5025G, was substantially damaged during a forced landing to an agricultural field in Gerrardstown, West Virginia. The commercial pilot was not injured. Visual meteorological conditions prevailed. No flight plan had been filed for the local flight, which originated at Eastern West Virginia Regional Airport/Shepherd Field (MRB), Martinsburg, West Virginia. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. According to the pilot, the airplane departed MRB about 1230, and during the flight, while maneuvering about 3,000 feet, the Mazda 13B rotary engine's coolant temperature rose. The pilot turned the airplane back toward the airport, and the engine seized and would not turn over during an attempted restart. The pilot advised MRB control tower personnel that he would have to land in a field, which included recently-planted apple trees. The pilot was able to land on a flat portion of the field; however, during the landing rollout, the airplane encountered a ditch that caught the nose wheel and bent the nose strut back, and the airplane nosed over. After the airplane was recovered from the field, the pilot, who was also the builder, disassembled the engine, which he stated had 4 hours of operation since it was rebuilt. The pilot first noted that the water pump, which was newly installed prior to the accident flight, had rust-colored water at the outlet hole from the pump bearing. The pilot also noted that a lot of metal had passed through the engine and the reduction drive, and that the stationary gear/bearing was frozen to the eccentric shaft. The pilot/builder further noted that during the recent rebuild, he had attempted to fine tune the engine by having the side and intermediate housings undergo lap grinding. The pilot/builder knew the grinding would require wider spacers, which he used, but those used may have been insufficient in width. The insufficient width resulted in bearing oil hole misalignment on the eccentric shaft which blocked oil from reaching rotating engine and reduction drive shaft parts. ## Aircraft - Registration: [N5025G](https://openairdocs.org/deregistered/N5025G-2019-01-18), registration cancelled 2019-01-18, S/N 71591, built 2006 (OpenAirDocs) - Reported make and model: PRENDERGAST JOHN/VANS RV-7A - Registry model: [Prendergast John/Vans RV-7A](https://openairdocs.org/model/prendergast-john-vans-rv-7a) (registry code 0561984) (OpenAirDocs) - Registry engine: [Mazda 13B](https://openairdocs.org/engine/mazda-13b) (registry code 43200, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 71591 - Airframe hours: 290 - Engines: MAZDA 13B 146 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: John Prendergast - Registered owner: Airnav Corp - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 19, 2011, 60 hours before - Departed: MRB, Martinsburg, WV - Destination: MRB, Martinsburg, WV ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 72; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review April 19, 2010; seat: left; flight hours: 3,196 total, 290 in this make and model, 2,000 as pilot in command, 4 in the last 90 days, 2 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 11 knots, gusting 16 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 88 °F, dew point 55 °F - Altimeter: 29.94 inHg - Observed at: MRB, 5 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 20120416007309A](https://openairdocs.org/incident/20120416007309A), Apr 16, 2012: Prendergast John/Vans RV-7A, Gerrardstown, WV, Substantial damage. Aircraft departed from mrb for local flight. Pilot stated engine water temperature started to rise very high. Engine then seized, causing the pilot to make a… ## Other investigations on N5025G (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 CHI08CA229](https://openairdocs.org/ntsb/CHI08CA229), Aug 1, 2008: Prendergast RV-7A (N5025G), Manchester, MI, substantial damage. Probable cause: The pilot's inadequate flare during landing. Contributing to the accident was the uneven terrain. ## Docket (6 files) The files NTSB released with the investigation on November 30, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83441. 10.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40374477&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Pilot/Builder Email Responses (item 2, .PDF, 36 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40380950&FileExtension=.PDF&FileName=Pilot%2FBuilder%20Email%20Responses%20-Redacted.PDF - Generic Rotary Engine Diagram (item 3, .PDF, 92 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40380951&FileExtension=.PDF&FileName=Generic%20Rotary%20Engine%20Diagram-Master.PDF - Generic Diagram Mazda 13B Eccentric Shaft and Flywheel (with Parts Nomenclature) (item 4, .PDF, 70 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40380949&FileExtension=.PDF&FileName=Generic%20Diagram%20Mazda%2013B%20Eccentric%20Shaft%20and%20Flywheel%20(with%20Parts%20Nomenclature)-Master.PDF - Photo 1 - Nose-Over Wreckage (Courtesy Berkley County Sherif's Department) (item 5, .PDF, 6.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40377164&FileExtension=.PDF&FileName=Photo%201%20-%20Nose-Over%20Wreckage%20(Courtesy%20Berkley%20County%20Sherif%27s%20Department)%20%20-Master.PDF - Photo 2 - Stationary Gear-Bearing Frozen to Eccentric Shaft (Courtesy Pilot/Builder) (item 6, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40377166&FileExtension=.PDF&FileName=Photo%202%20-%20Stationary%20Gear-Bearing%20Frozen%20to%20Eccentric%20Shaft%20(Courtesy%20Pilot%2FBuilder)-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.