# NTSB DFW08CA079: Willey Rotorway Exec 90, N5251B, Westport, OK, March 8, 2008 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: March 8, 2008, 15:00 local (20:00 UTC) - Place: Westport, OK - Coordinates: 36.222221, -96.344444 - Nearby events: https://openairdocs.org/map.md?lat=36.2222&lon=-96.3444&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Electrical system malf/failure](https://openairdocs.org/ntsb-events/332) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report April 30, 2008 - Report: Approved by Office Director - Parties: FAA FSDO - NTSB case key (mKey): 67640 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DFW08CA079 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/67640/pdf - Page: https://openairdocs.org/ntsb/DFW08CA079 ## Probable cause An unsuccessful precautionary landing due to an electrical system malfunction. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Electrical power system](https://openairdocs.org/ntsb-findings/01022400): Aircraft › Aircraft systems · Malfunction (probable cause); cases with it: [Willey S/Willey E EXEC 90, 1 case](https://openairdocs.org/ntsb-findings/01022400/cases.md?model=05626EK), [All aircraft, 48 cases](https://openairdocs.org/ntsb-findings/01022400/cases.md) - [Runway/land/takeoff/taxi surface: soft surface](https://openairdocs.org/ntsb-findings/03023020): Environmental issues › Physical environment · Not specified (probable cause); cases with it: [Willey S/Willey E EXEC 90, 1 case](https://openairdocs.org/ntsb-findings/03023020/cases.md?model=05626EK), [All aircraft, 264 cases](https://openairdocs.org/ntsb-findings/03023020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Electrical system malf/failure](https://openairdocs.org/ntsb-events/332) (defining event); cases with it: [Willey S/Willey E EXEC 90, 1 case](https://openairdocs.org/ntsb-events/332/sequence.md?model=05626EK), [All aircraft, 182 cases](https://openairdocs.org/ntsb-events/332/sequence.md) - [Autorotation: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Willey S/Willey E EXEC 90, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05626EK), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The certified flight instructor and the student pilot were on an instructional flight to practice autorotations and simulated engine failures. About 45 minutes into the flight the instructor noticed the engine tachometer read lower than the rotor tachometer. The student pilot checked the battery voltage and said that it was "low". The instructor reported that the engine's fuel pump and ignition systems were not independent and he did not want to risk a downwind autorotation landing. When the instructor saw the rotor tachometer drop to 90 percent, he initiated an autorotation, assuming the helicopter had or was about to lose engine power. During the landing the left skid sank into the soft terrain and the helicopter subsequently rolled on to its side. The helicopter sustained substantial damage during the precautionary landing. ## Factual narrative The certified flight instructor and the student pilot were on an instructional flight to practice autorotations and simulated engine failures. About 45 minutes into the flight the instructor noticed the engine tachometer read lower than the rotor tachometer. The student pilot checked the battery voltage and said that it was "low". The instructor reported that the engine's fuel pump and ignition systems were not independent and he did not want to risk a downwind autorotation landing. When the instructor saw the rotor tachometer drop to 90 percent, he initiated an autorotation, assuming the helicopter had or was about to lose engine power. During the landing the left skid sank into the soft terrain and the helicopter subsequently rolled on to its side. The helicopter sustained substantial damage during the precautionary landing. ## Aircraft - Registration: [N5251B](https://openairdocs.org/deregistered/N5251B-2013-07-29), registration cancelled 2013-07-29, S/N 5251, built 1995 (OpenAirDocs) - Reported make and model: Willey Rotorway Exec 90 - Registry model: [Willey S/Willey E EXEC 90](https://openairdocs.org/model/willey-s-willey-e-exec-90) (registry code 05626EK) (OpenAirDocs) - Registry engine: [Rotorway RW-100 series](https://openairdocs.org/engine/rotorway-rw-100-series) (registry code 55001, reciprocating) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 5251 - Airframe hours: 983 - Engines: Rotorway RW-100 reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, March 1, 2008 - Departed: 95F, CLEVELAND, OK - Destination: 4F1, WESTPORT, OK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 48; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review November 1, 2007; seat: front; flight hours: 498 total, 22 in this make and model, 113 in the last 90 days, 19 in the last 30 days, 5 in the last 24 hours - Student pilot; age 32; injuries: none; sport pilot; airplane ratings: single-engine land; medical: sport pilot ## Weather - Conditions: Visual (VMC), Day - Wind: 10° at 12 knots, gusting 16 - Visibility: 10 statute miles - Lowest ceiling: 6,000 ft overcast - Temperature: 36 °F, dew point 23 °F - Altimeter: 30.13 inHg - Observed at: KRVS, 20 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 20080308012169A](https://openairdocs.org/incident/20080308012169A), Mar 8, 2008: Amtr EXEC90, Westport, OK, Substantial damage. (-23) On March 8, 2008, N5251B, an experimental helicopter, was on a local instructional flight at 1545. On the flight back to the airport of origin, Westport… 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.