# NTSB FTW97LA156: Rockwell 114, N4861W, Oklahoma City, OK, April 7, 1997 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 7, 1997, 17:14 local (23:14 UTC) - Place: Oklahoma City, OK - Coordinates: 35.479846, -97.650596 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.4798&lon=-97.6506&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 2, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 20196 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW97LA156 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/20196/pdf - Page: https://openairdocs.org/ntsb/FTW97LA156 ## Probable cause The exhaust manifold cracking due to the pilot's inadequate maintenance modification of the exhaust system which resulted in a fire. A factor was the lack of suitable terrain for the forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, takeoff - initial climb - exhaust system,manifold/pipe - cracked (cause) - maintenance,modification - inadequate, pilot in command (cause) - Fire, approach - vfr pattern - downwind - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, landing - roll - terrain condition - none suitable (contributing factor) - terrain condition - berm - terrain condition - soft - object - fence - object - fence post ## Analysis The engine lost power and an in flight fire sent smoke into the cabin during initial takeoff climb on a local maintenance flight of a prototype exhaust system. During the forced landing, short of the runway, the airplane touched down in soft soil, crossed a gravel driveway and struck an embankment and a fence before coming to a stop. Subsequently the airplane was consumed by the fire. The airframe was inspected by the FAA inspector and he found an unapproved modification, designed by the pilot, for the cowling and the exhaust system. The exhaust system components were wrapped in a heat protective tape approximately 2 inches wide. After removing the exhaust from the engine and removing the tape, it was found that the right hand exhaust pipe collector was cracked in several areas. The pilot reported that he was working on a STC for drag reduction and the experimental exhaust manifold cracked at the weld after 7 hours of test flights. ## Factual narrative On April 7, 1997, at 1714 central standard time, a Rockwell International 114, N4861W, owned by Montana Engine Rebuilders, Inc., at Billings, Montana, and operated by a private individual under Title 14 CFR Part 91, was destroyed following an in flight fire and forced landing near Oklahoma City, Oklahoma. The private pilot egressed prior to the destruction of the airplane and he was not injured. Visual meteorological conditions prevailed for the local maintenance test flight and a flight plan was not filed. The flight was originating at the time of the emergency. During an interview, conducted by the investigator-in-charge (IIC), and on the Pilot/Operator Report, the pilot reported that during initial takeoff climb from runway 17 at the Sundance Airpark he noticed a "hot" smell due to the thermal wrapping material around the exhaust pipes. As the smell was growing stronger, the pilot made a downwind entry for the runway. Smoke entered the cabin and during the downwind to base entry for the landing there was a partial loss of engine power. By the time the airplane was turned onto base, a total loss of engine power occurred and a forced landing was made short of the runway with the initial touchdown point about 1/2 mile north and 900 feet west of the runway. The airplane touched down in soft soil and during the landing roll the airplane crossed a gravel driveway, and struck an embankment and a fence before coming to a stop. After exiting the airplane, the pilot noted flames coming from the bottom of the firewall and engine compartment. Subsequently the airplane was consumed by the fire. The pilot reported that he was working on a Supplemental Type Certificate (STC) for drag reduction in the make and model of aircraft. The exhaust system and cowling were a prototype with about 7 hours of test flights completed. He reported on the Pilot/Operator Report that the experimental part of the exhaust manifold cracked at the weld. During an interview, the owner reported to the IIC that his aircraft was flown from Montana to Oklahoma about 3 years ago. The pilot, who was a design engineer, was utilizing the airplane for testing a speed modification design. A former employee of the pilot reported that the aircraft had been "extensively and illegally modified." The list included " unapproved engine cowling, cowling barrier material, and the muffler system." On April 30, 1997, the airframe was inspected by the FAA inspector who found an unapproved modification of the cowling and the exhaust system. The exhaust system components were wrapped in a heat protective tape approximately 2 inches wide. After removing the exhaust from the engine and removing the tape, it was found that the right hand exhaust pipe collector was cracked in several areas. For additional details see the enclosed FAA inspector statement. ## Aircraft - Registration: [N4861W](https://openairdocs.org/deregistered/N4861W-1998-04-18), registration cancelled 1998-04-18, S/N 14191 (OpenAirDocs) - Reported make and model: Rockwell 114 - Registry model: [Rockwell International 114](https://openairdocs.org/model/rockwell-international-114) (registry code 7630314) (OpenAirDocs) - Category: Airplane - Serial number: 14191 - Airframe hours: 2000 - Engines: Lycoming IO-540 260 horsepower reciprocating - Damage: Destroyed - Fire: In-Flight - Flight: Part 91 - Operator: Robert K. Cordray - Registered owner: Montana Engine Rebuilders, Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 22, 1996, 14 hours before - Departed: HSD - Airport: HSD, Sundance Airpark ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; private; airplane ratings: single-engine land; medical: class 3, expired; seat: left; flight hours: 295 total, 182 in this make and model, 261 as pilot in command, 6 in the last 90 days, 2 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 18 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 57 °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 19970407010199A](https://openairdocs.org/incident/19970407010199A), Apr 7, 1997: Gulstm 114, Oklahoma City, OK, Destroyed. Hot smell on test flight. Enigne quit turning base. Landed short. Burned. Exhaust weld broke. Illegal modification. (-23) aircraft had smoke in cabin shortly… 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.