# NTSB LAX97LA014: Cunningham Rotorway Exec, N18WC, Mather, CA, October 13, 1996 - Type: NTSB accident investigation - Classification: Accident · Fatal · Limited investigation · Final report - Date: October 12, 1996, 17:55 local (Oct 13, 1996, 00:55 UTC) - Place: Mather, CA - Coordinates: 38.54018, -121.280967 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.5402&lon=-121.2810&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 1 fatal - Status: Completed, report October 31, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 29662 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX97LA014 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29662/pdf - Page: https://openairdocs.org/ntsb/LAX97LA014 ## Probable cause excessive maneuvering by the pilot, which allowed the main rotor blades to contact and sever the tail rotor system and allowed mast bumping to occur. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Abrupt maneuver, maneuvering - low altitude flight/maneuver - initiated, pilot in command - maneuver - excessive, pilot in command (cause) - Airframe/component/system failure/malfunction, maneuvering - rotor system,main rotor blade - unapproved - misc rotorcraft,main rotor/tail boom contact - rotor system,main rotor blade - separation - mast bumping - In flight collision with terrain/water, descent - uncontrolled ## Analysis The pilot of a home built helicopter was attempting to drop an object (bag of flour) to a target on the ground. Approaching the target area, the helicopter was observed to maneuver, then it went out of control and crashed. Investigation revealed evidence that the main rotor blades contacted and severed the tailboom. Also, there was evidence of mast bumping. The helicopter was equipped with composite main rotor blades; kit/factory approved blades were made of metal. No mechanical malfunction was found. ## Factual narrative On October 12, 1996, at 1755 hours Pacific daylight time, an experimental Rotorway Exec helicopter, N18WC, crashed at Mather Airport, Mather, California. The pilot was conducting a local visual flight rules personal flight. The helicopter, registered to and operated by the pilot, was destroyed by impact forces and the resulting postimpact fire. The certificated private pilot, the sole occupant, sustained fatal injuries. Visual meteorological conditions prevailed with the winds estimated by witnesses to be at 10 to 15 miles per hour with gusts. The flight departed Mather Airport at an undetermined time. Ground witnesses reported that they observed the helicopter execute a hard right turn followed by a hard left turn with some oscillations. During this maneuver, the main rotor blades struck the tailboom. The helicopter entered an uncontrolled descent, crashed and burned. Examination of the wreckage revealed that the main rotor blades were of a composite material and not the aluminum blades authorized by the manufacturer. There was evidence of some mast bumping next to the teeter stops behind the thrust stops. There was no evidence found of a mechanical malfunction. According to a manufacturer representative at the accident site, he was informed by other pilots that the accident pilot was making a bomb run over a ground target using a bag of flour. He was told that a bag of flour was somewhere in the cabin area and the helicopter was at the correct location over the target area when the accident sequence began. ## Aircraft - Registration: [N18WC](https://openairdocs.org/deregistered/N18WC-1997-01-17), registration cancelled 1997-01-17, S/N WPC001 (OpenAirDocs) - Reported make and model: Cunningham ROTORWAY EXEC (ROTORWAY E) - Registry model: [Cunningham W E ROTORWAY EXEC](https://openairdocs.org/model/cunningham-w-e-rotorway-exec) (registry code 13017LT) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: WPC001 - Airframe hours: 80 - Engines: Rotorway reciprocating - Damage: Destroyed - Fire: On-Ground - Flight: Personal, Part 91 - Registered owner: William E. Cunningham - Airworthiness certificate: Special, Experimental (Special) - Departed: MHR - Airport: MHR, Sacrmento Mather ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; private; medical: class 3, valid medical--w/ waivers/lim; seat: right; toxicology performed; flight hours: 100 total, 100 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 10 knots - Visibility: 20 statute miles - Lowest ceiling: 20,000 ft broken - Temperature: 77 °F, dew point 57 °F - Altimeter: 29.00 inHg - Observed at: SAC ## 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 19961013031979A](https://openairdocs.org/incident/19961013031979A), Oct 13, 1996: Amtr ROTORWAYEXEC, Sacramento, CA, Destroyed, 1 fatal. Helicopter made hard left turn, followed by hard right, main rotor struck tail rotor. Crashed and burned. (.19) on October 12, 1996, at 1755 hours pacific… 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.