LAX94LA083

NTSB accident investigation · Rotorway EXEC-90 · Scottsdale, AZ · December 28, 1993

Accident · Minor injuriesLimited investigationFinal report
Date
December 28, 1993, 11:20 local (18:20 UTC)
Place
Scottsdale, AZ
Injuries
1 minor
Damage
Destroyed
Phase of flight
Enroute
Aircraft
N7456TRotorway EXEC-90
Weather
Visual (VMC) · Day
Status
Completed · report September 13, 1994
Report
Approved by Office Director
FAA report
19931228047329A
Case key
28629

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

A failure of the pilot-in-command to adequately conduct a preflight inspection and properly secure a fuselage cowling panel that struck a tail rotor blade, resulting in a subsequent failure of the tail rotor drive system. Factors in this accident were an in-flight separation of the cowling panel, and the inability of the pilot to effect directional control of the helicopter.

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.

Loss of control - in flightCruise
Fuselage,fairing - not securedCause
Aircraft preflight - inadequatePilot in commandCause
Fuselage,fairing - separationFactor
Rotor system,tail rotor blade - foreign object damageCause
Rotor drive system,tail rotor drive shaft - failure,totalCause
Directional control - not possiblePilot in commandFactor
Forced landingDescent - emergency
Hard landingDescent - emergency

Analysis

Prior to the accident flight, the helicopter was examined by the FAA and issued an experimental airworthiness certificate. The aircraft then departed on a ferry flight of two helicopters to return to the helicopter company building. After departure, the second aircraft observed an object go through the rotor system of the accident helicopter. The pilot began a precautionary landing and, subsequently, experienced an anti-torque system failure. After touchdown, a postcrash fire consumed 2/3 of the aircraft. One tail rotor blade had been struck by a fiberglass cowling panel that was later located along the flight path.

Factual narrative

On December 28, 1993, about 1120 hours mountain standard time, a Rotorway Exec-90 helicopter, N7456T, crashed during a forced landing about 6 miles east of Scottsdale, Arizona. The helicopter was being operated as a visual flight rules (VFR) cross-country ferry flight to Stellar Airpark, Chandler, Arizona, when the accident occurred. The helicopter, operated by Rotorway International, was destroyed by impact and postimpact fire. The certificated commercial pilot, the sole occupant, received minor injuries. Visual meteorological conditions prevailed. The flight originated from the Scottsdale Municipal Airport about 1115 hours.

The pilot reported that the helicopter was one of two aircraft being ferried back to the factory after having been inspected at the Federal Aviation Administration (FAA) Scottsdale Fight Standards District Office (FSDO). After departure, the pilot heard a "popping" sound, and the pilot of the second helicopter in the flight observed an unknown object go through the accident helicopter's rotor system. The pilot began a precautionary landing approach to an open area. During the approach, the pilot began to smell burning rubber and suspected a malfunction of the tail rotor drive belts.

Several seconds later, the pilot heard and felt a "bang" and the helicopter began to spin to the left. The pilot applied right rudder pedal with no response, and attempted to control the helicopter by utilizing varying amounts of power, collective, and cyclic pitch. The helicopter descended at a high rate and struck the ground in a level attitude, collapsing the landing gear skids. After ground impact, a fire began near the engine compartment and consumed about 2/3 of the helicopter.

An FAA operations inspector from the Scottsdale FSDO inspected the helicopter at the accident site. He reported that one tail rotor blade exhibited an aft crush and splitting of the leading edge of the blade at the outboard end. He also reported that a portion of a fiberglass cowling panel was located in a field, southeast of the Scottsdale airport, along the helicopters' route of flight. The panel was fragmented into several pieces and is normally attached by "dzus" fasteners to the top area of helicopter cowling. The underside of the panel exhibited "56T" written on the cowl.

The helicopter had accumulated a total time in service of 612.2 flight hours. Examination of the maintenance records revealed the most recent inspection was accomplished on December 27, 1993. The accident flight was the first flight following inspection by the FAA Manufacturing Inspection Satellite Office (MISO), Scottsdale, and issuance of an experimental airworthiness certificate for the purpose of market survey.

Aircraft

Registration
N7456T
Reported as
Rotorway EXEC-90
Category
Helicopter
Serial number
RI5001
Airframe hours
612
Engine
Rotorway R-162, 125 horsepower, reciprocating
Damage
Destroyed
Fire
On-Ground
Flight
Ferry · Part 91
Operator
Cobb International, doing business as Rotorway International
Registered owner
Cobb International
Airworthiness certificate
Special, Experimental (Special)
Last inspection
Continuous airworthiness · December 27, 1993 · 1 hours before
Destination
P19 · Chandler, AZ

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
45
Certificates
Flight instructor, Commercial
Airplane ratings
Single-engine land
Instrument ratings
Airplane
Medical
Class 2, Valid Medical--no waivers/lim.
Seat
Left
Flight hours
1,979 total · 250 in this make and model · 1,756 as pilot in command · 108 in the last 90 days · 37 in the last 30 days · 1 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
190° at 4 knots
Visibility
45 statute miles
Lowest ceiling
None
Temperature
61 °F, dew point 36 °F
Observed at
SDL, 6 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.

Other investigations on N7456T · 1

Matched to the same aircraft by N-number and date.