FTW98LA182

NTSB accident investigation · Froberg Rotorway Executive · Sand Springs, OK · April 13, 1998

Accident · No injuriesLimited investigationFinal report
Date
April 13, 1998, 18:45 local (23:45 UTC)
Place
Sand Springs, OK
Injuries
1 uninjured
Damage
Destroyed
Phase of flight
Enroute
Aircraft
N71RFFroberg Rotorway Executive
Weather
Visual (VMC) · Day
Status
Completed · report February 15, 2001
Report
Approved by Office Director
FAA report
19980413006739A
Case key
20579

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

The failure of the owner/pilot to complete maintenance on 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.

FireCruise - normal
Engine assembly
Maintenance - not performedOwner/pilot mechanicCause
Fluid,oil - leakCause
Exhaust system,manifold/pipe
Forced landingEmergency descent/landing
Autorotation - performedPilot in command
Terrain condition - high vegetationFactor

Analysis

The pilot reported that he was flying the Froberg Rotorway Executive experimental helicopter to the William R. Pogue Municipal Airport, Sand Springs, Oklahoma, for fuel. Approximately 6 minutes after takeoff, the pilot observed smoke entering the cockpit from the right side and noted a loss of oil pressure. He executed an autorotation to a field of tall dry grass and exited the helicopter. After exiting the aircraft, the pilot observed a fire underneath the helicopter. The aircraft was then consumed by the fire within a few minutes. The pilot reported to the FAA inspector that 'there was an oil leak and oil was dripping on the exhaust pipe.' The pilot had purchased the helicopter about a year prior to the accident. He had flown the aircraft about 30 hours since purchasing it and had not registered it. No maintenance had been performed on the helicopter in the last 20 hours.

Factual narrative

On April 13, 1998, at 1845 central daylight time, a Froberg Rotorway Executive experimental helicopter, N71RF, owned and operated by a private individual as a Title 14 CFR Part 91 personal flight, was destroyed after a forced landing following an in-flight fire near Sand Springs, Oklahoma. Visual meteorological conditions prevailed, and a flight plan was not filed. The private pilot, sole occupant of the helicopter, was not injured. The flight originated from West Port, Oklahoma, approximately 6 minutes prior to the accident.

The pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he was flying the helicopter to the William R. Pogue Municipal Airport, Sand Springs, Oklahoma, for fuel. Approximately 6 minutes after takeoff, the pilot observed smoke entering the cockpit from the right side and noted a loss of oil pressure. He executed an autorotation to a field of tall dry grass and exited the helicopter. He further reported that after exiting the aircraft, he observed a fire underneath the helicopter. The aircraft was then consumed by the fire within a few minutes.

The pilot reported to the FAA inspector that "there was an oil leak and oil was dripping on the exhaust pipe."

Examination of the aircraft wreckage by the FAA inspector revealed that it was destroyed by the fire.

According to the FAA inspector, the pilot had purchased the Froberg Rotorway Executive helicopter about a year prior to the accident. The pilot had flown the aircraft about 30 hours since purchasing it and had not registered it. No maintenance had been performed on the helicopter in the last 20 hours.

Aircraft

Registration
N71RF
Reported as
Froberg Rotorway Executive (ROTORWAY E)
Category
Helicopter, amateur-built
Serial number
1092
Engine
Rotorway ROTORWAY 145, 150 horsepower, reciprocating
Damage
Destroyed
Fire
In-Flight
Flight
Personal · Part 91
Operator
John T. Spurling
Registered owner
Ronald Froberg
Airworthiness certificate
Special, Experimental (Special)
Departed
4F1 · West Port, OK
Destination
0F8 · Sand Springs, OK

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
40
Certificate
Private
Airplane ratings
Single-engine land
Medical
Class 3, Valid Medical--w/ waivers/lim
Seat
Left
Flight hours
580 total · 30 in this make and model · 30 in the last 90 days · 14 in the last 30 days · 3 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Visibility
10 statute miles
Lowest ceiling
None
Temperature
81 °F

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.