Redmond, OR, USA
N117KR
PIPER PA-46-350P
The pilot reported that during the approach to the airport, the landing gear down and locked indicator lights (3-green) did not illuminate when the landing gear handle was placed in the down position. The pilot cycled the landing gear; however, the landing gear lights did not illuminate and the pilot activated the emergency landing gear extension system and declared an emergency. After the emergency was declared, the pilot noted flames emanating from the engine cowling and the cockpit began to fill with smoke. Shortly thereafter tower personnel reported that the airplane was trailing smoke and the pilot was cleared to land. The pilot reported that on short final to the runway the "engine experienced a significant, uncommanded decrease in power, but continued to provide partial power." After landing, the pilot and passenger exited the airplane and the fire was extinguished by airport fire department personnel. Examination of the airframe and engine revealed that the nose landing gear hydraulic actuator hose was separated from its corresponding B-nut coupler. The B-nut fitting remained attached to the threaded end of the hydraulic actuator; however, the hose was separated from the coupler at the coupler flange. The hose was covered by dark soot and extensive thermal damage was noted. The opposing end of the hydraulic hose was secured to its associated coupler and fitting. The hydraulic hose is positioned below the engine, adjacent to the turbo charger and exhaust. The examination also revealed that the upper right crossover exhaust pipe was separated from the intermediate crossover exhaust pipe. Fire damage was noted on both the internal and external exposed ends of both the intermediate and right crossover exhaust pipes in the area where they were intended to be connected. The hydraulic hose and associated coupler were removed from the airframe and examined by Safety Board investigators. Due to the extensive thermal damage, the failure mode of the hose was not determined, and the correlation between the exhaust leak and separated hydraulic hose was not established. Subsequent to the accident, the manufacturer amended the maintenance manual for the airplane to reflect changes in the service life limits for nose landing gear hydraulic hoses. The amendment states "Replace nose gear hydraulic hoses (gear actuator/door actuator/ sequence valve), as required; but do not exceed 1,000 hours time-in-service, or eight (8) years, whichever comes first."
HISTORY OF FLIGHT On July 21, 2009, about 1400 Pacific daylight time, a Piper PA-46-350P airplane, N117KR, sustained substantial damage following an in-flight engine compartment fire and subsequent emergency landing at Roberts Field Airport (RDM), Redmond, Oregon. The private pilot and passenger were not injured. The airplane was registered to the pilot and was operated as a visual flight rules (VFR) cross-country flight under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed at the time of the accident. The flight originated at Novato, California, at 1200, and was en route to Sun River, Oregon. No flight plan was filed. The pilot reported that during the approach to an uncontrolled airport, the landing gear "down and locked" indicator lights (3-green) did not illuminate when the landing gear handle was placed in the down position. The pilot "cycled" the landing gear and verified that the landing gear circuit breaker was in the closed position; however, the landing gear lights did not illuminate, and the pilot activated the emergency landing gear extension system. The pilot stated that he then declared an emergency and received vectors to a nearby controlled airport where he was cleared for a low altitude tower fly-by. Tower personnel reported to the pilot that it appeared that the landing gear was "down and locked" and cleared the pilot to land. The pilot reported that on the downwind leg for runway 28 he noted flames emanating from the engine cowling and the cockpit began to fill with smoke. The pilot reported the fire to the control tower and his clearance was amended and cleared to land on runway 04. The pilot reported that on short final to the runway the "engine experienced a significant, uncommanded decrease in power, but continued to provide partial power." Air traffic control tower personnel reported that they observed smoke trailing the airplane as it approached the airport and that flames were observed underneath the airplane's engine compartment during the landing flare. After landing, the pilot and passenger exited the airplane and the fire was extinguished by airport fire department personnel. AIRCRAFT INFORMATION The airplane was manufactured in 1997, and was equipped with a Lycoming TIO-540-AE2A engine, serial number RL-8536-61A. A review of the maintenance logbooks revealed that the airframe received an annual inspection on January 5, 2009 at a total airframe time of 1,769.6 hours, approximately 48 flight hours prior to the accident. The maintenance logbooks also indicated that the engine was removed from the airframe and received a major overhaul on December 16, 2008. Subsequent to the overhaul, the engine was reinstalled and an annual inspection was completed on January 5, 2009, at a total engine time of 1,769.6; approximately 48 flight hours prior to the accident. The maintenance records further indicated that the most recent maintenance action on the airplane was an engine oil filter and oil change on July 21, 2009, approximately 2 flight hours prior to the accident. TESTS AND RESEARCH Airframe and Engine Examination Extensive fire damage was noted to the forward fuselage baggage compartment and engine compartment. Dark soot was observed throughout the engine compartment and aft engine cowling seam. Soot and thermal discoloration was noted to the aft engine accessories, firewall and firewall components. Thermal damage and soot was noted to a majority of the engine compartment fluid and air hoses. The examination revealed that the nose landing gear hydraulic actuator hose (part number 63901-041) was separated from its corresponding B-nut coupler. The B-nut fitting remained attached to the threaded end of the hydraulic actuator; however, the hose was separated from the coupler at the coupler flange. The hose was covered by dark soot and extensive thermal damage was noted. The opposing end of the hydraulic hose was secured to its associated coupler and fitting. The hydraulic hose was positioned below the engine, adjacent to the turbo charger and exhaust. A second examination of the engine was conducted after it was removed from the airframe. The exam revealed that the right crossover exhaust pipe bracket was not secured to its associated mounting stud on the lower intake tubing. Removal of the heat shield from the exhaust assembly revealed that the upper right crossover exhaust pipe was separated from the intermediate crossover exhaust pipe. Fire damage was noted on both the internal and external exposed ends of both the intermediate and right crossover exhaust pipes in the area where they were intended to be connected. Examination of the connection between the right crossover exhaust pipe and the right aft exhaust manifold tubing revealed that the clamp securing the two appeared to be offset or not centered. Disassembly of the connection revealed that two thin metal gaskets were between the manifold and pipe. The first metal gasket was removed without issue and measured 0.015 inches. This gasket contained the signature lip which allows for the proper alignment between the crossover exhaust pipe and the exhaust manifold tubing. The second metal gasket separated into several pieces when removal was attempted. Examination reports with accompanying photographs are contained within the public docket for the accident case file. ADDITIONAL INFORMATION The hydraulic hose and associated coupler were removed from the airframe and examined by Safety Board investigators. Due to the extensive thermal damage, the failure mode/sequence was not determined. A review of the aircraft's maintenance records revealed no evidence to indicate the nose landing gear hydraulic actuator hose had been replaced at anytime during the service life of the aircraft. A review of the Piper PA-46-350P Maintenance Manual (part number 761-876, dated July 31, 2008) indicated that the before mentioned hydraulic hose has a maximum service life of 20-years. Subsequent to the accident (September 15, 2009), Piper Aircraft amended the maintenance manual for the PA-46-350P to reflect changes in the service life limits for nose landing gear hydraulic hoses. The "Special Inspections" section of the manual (paragraph G, item 2) states "Replace nose gear hydraulic hoses (gear actuator/door actuator/ sequence valve), as required; but do not exceed 1,000 hours time-in-service, or eight (8) years, whichever comes first." On February 10, 1995, Lycoming issued Mandatory Service Bulletin (MSB) No.521. The MSB outlined detailed inspection criteria for the exhaust system. The MSB stated, in part, that the inspections are to ensure proper engagement for each slip joint of the exhaust system. The MSB required the inspection to be accomplished at the next scheduled maintenance event; not to exceed 50 hours of operation, and annually or every 250 hours of operation, whichever comes first. A logbook entry associated with the engine overhaul, dated December 16, 2008, indicated that all engine service bulletins had been complied with.
An undetermined hydraulic system malfunction in the engine compartment during descent from cruise flight which resulted in an in-flight fire.
Source: NTSB Aviation Accident Database
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