# NTSB FTW98LA182: Froberg Rotorway Executive, N71RF, Sand Springs, OK, April 13, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 13, 1998, 18:45 local (23:45 UTC) - Place: Sand Springs, OK - Coordinates: 36.129581, -96.129364 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.1296&lon=-96.1294&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 15, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 20579 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW98LA182 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/20579/pdf - Page: https://openairdocs.org/ntsb/FTW98LA182 ## Probable cause The failure of the owner/pilot to complete maintenance on the helicopter. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Fire, cruise - normal - engine assembly - maintenance - not performed, owner/pilot mechanic (cause) - fluid,oil - leak (cause) - exhaust system,manifold/pipe - Forced landing, emergency descent/landing - autorotation - performed, pilot in command - terrain condition - high vegetation (contributing factor) ## 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](https://openairdocs.org/deregistered/N71RF-2013-05-08), registration cancelled 2013-05-08, S/N 1092, built 1992 (OpenAirDocs) - Reported make and model: FROBERG ROTORWAY EXECUTIVE (ROTORWAY E) - Registry model: [Froberg Ronald D ROTORWAY EXECUTIVE](https://openairdocs.org/model/froberg-ronald-d-rotorway-executive) (registry code 13015KF) (OpenAirDocs) - Registry engine: [Rotorway RW-145 series](https://openairdocs.org/engine/rotorway-rw-145-series) (registry code 55005, reciprocating) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 1092 - Engines: 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 ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; 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 (OpenAirDocs). - [Accident 19980413006739A](https://openairdocs.org/incident/19980413006739A), Apr 13, 1998: Amtr ROTORWAYEXEC, Sand Springs, OK, Destroyed. On April 13, 1998, at 1845 central daylight time a froberg rotorway executive ecperimental helicopter, N71RF, owned by a private individaul as a title 14 CFR… 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.