# NTSB CHI07CA124: Wilkinson Daniel V Rotorway Exec 90, N52988, Kalamazoo, MI, April 28, 2007 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: April 28, 2007, 12:52 local (16:52 UTC) - Place: Kalamazoo, MI - Coordinates: 42.288887, -85.75 - Nearby events: https://openairdocs.org/map.md?lat=42.2889&lon=-85.7500&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 27, 2007 - Report: Approved by Office Director - NTSB case key (mKey): 65840 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI07CA124 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/65840/pdf - Page: https://openairdocs.org/ntsb/CHI07CA124 ## Probable cause The failure of the sprag clutch which resulted in the disengagement of the drive unit and the pilot's misjudged landing during the autorotation. A factor was the low altitude at which the failure occurred. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, maneuvering - rotor drive system,freewheeling sprag unit - failure (cause) - altitude - low, pilot in command (contributing factor) - Forced landing, emergency descent/landing - autorotation - performed, pilot in command - terrain condition - grass - Roll over, emergency landing - touchdown - misjudged, pilot in command (cause) - Fire, other ## Analysis The helicopter was destroyed by impact forces and a post crash fire while attempting an auto-rotation after a mechanical failure. The pilot stated that he was practicing takeoffs, hovering, and quick stops above the runway. After takeoff, at about 50 feet and 50mph, he lowered the collective to initiate a quick stop. At this point the engine RPM revved up out of control. He pulled up on the collective to re-engage the drive system, but the system would not engage. He entered into an auto-rotation, and as he neared the ground the helicopter began to slide sideways, folding the skids under the helicopter. The helicopter then rolled on its side, and the occupants climbed out prior to the post crash fire. Subsequent examination of the helicopter's drive system revealed that the drive shafts, pulleys, and drive belts were intact. The only device within the helicopter drive system that could not be determined to be in working condition was the sprag clutch which transmits engine power to the rotor drive system. The sprag clutch was not examined during the course of the investigation. ## Factual narrative The helicopter was destroyed by impact forces and a post crash fire while attempting an auto-rotation after a mechanical failure. The pilot stated that he was practicing takeoffs, hovering, and quick stops above the runway. After takeoff, at about 50 feet and 50mph, he lowered the collective to initiate a quick stop. At this point the engine RPM revved up out of control. He pulled up on the collective to re-engage the drive system, but the system would not engage. He entered into an auto-rotation, and as he neared the ground the helicopter began to slide sideways, folding the skids under the helicopter. The helicopter then rolled on its side, and the occupants climbed out prior to the post crash fire. Subsequent examination of the helicopter's drive system revealed that the drive shafts, pulleys, and drive belts were intact. The only device within the helicopter drive system that could not be determined to be in working condition was the sprag clutch which transmits engine power to the rotor drive system. The sprag clutch was not examined during the course of the investigation. ## Aircraft - Registration: [N52988](https://openairdocs.org/deregistered/N52988-2008-12-18), registration cancelled 2008-12-18, S/N 1, built 1994 (OpenAirDocs) - Reported make and model: Wilkinson Daniel V Rotorway Exec 90 - Registry model: [Wilkinson Daniel V ROTORWAY EXEC 90](https://openairdocs.org/model/wilkinson-daniel-v-rotorway-exec-90) (registry code 05624U3) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 1 - Engines: Rotorway RI-162 150 horsepower reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Departed: 4N0, Kalamazoo, MI - Airport: PVT, runway 18, 2,697 × 125 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; flight hours: 463 total, 433 in this make and model, 2 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 63 °F, dew point 46 °F - Altimeter: 29.87 inHg - Observed at: KAZO, 9 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 20070428009159A](https://openairdocs.org/incident/20070428009159A), Apr 28, 2007: Amtr EXEC90, Kalamazoo, MI, Destroyed. (-23) Pilot was practicing take-offs, hover, and quick stops above the runway. After take-off, at about 50 ft. and 50 mph, the pilot lowered the collective to… 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.