- Date
- October 12, 1996, 17:55 local (Oct 13, 1996, 00:55 UTC)
- Place
- Mather, CA
- Injuries
- 1 fatal
- Damage
- Destroyed
- Phase of flight
- Maneuvering
- Aircraft
- N18WCCunningham Rotorway Exec
- Weather
- Visual (VMC) · Day
- Status
- Completed · report October 31, 1997
- Report
- Approved by Office Director
- FAA report
- 19961013031979A
- Case key
- 29662
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
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
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
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
- Reported as
- Cunningham Rotorway Exec (ROTORWAY E)
- Category
- Helicopter, amateur-built
- Serial number
- WPC001
- Airframe hours
- 80
- Engine
- 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
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 50
- Certificate
- 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.