ANCHORAGE, AK, USA
N15
Beech F-90
During a practice instrument approach to Kenai Municipal Airport, the airplane's landing gear was extended. The first pilot noted the gear extension seemed different from previous extensions, in that the gear seemed to "hang" momentarily before completing the extension cycle. Coincidental with the lowering of the landing gear, the right engine fire bottle discharge light illuminated. The pilot initiated a missed approach and returned to Anchorage. After arrival in the Anchorage area, the pilots attempted to lower the landing gear via normal extension procedures. The first pilot reported that the indicator light for the right main gear did not illuminate. After confirming that the right main gear was not down, he made numerous attempts to extend the landing gear via normal procedures and manual gear extension procedures. After determining that the right main landing gear could not be extended, the first pilot elected to perform a wheels-up landing to runway 14. Postaccident examination of the airplane revealed that the right landing gear upper and lower drag leg had separated as a unit from its attach point on the forward wing spar. The support bracket and rib assembly for the drag leg were still attached to the upper drag link. Two longitudinal formers located between the forward and aft spars were buckled. Black, tire-like, skid marks were noted on the inside surface of the landing gear door. The airplane was placed on jacks and the landing gear was functionally checked. During the extension sequence, it was noted that the right main gear tire jammed on the inside of the outboard landing gear door, preventing the gear from completing its extension cycle. The left main gear and nose gear completed the extension cycle and the two associated down indication lights illuminated.
HISTORY OF FLIGHT On September 12, 2000, about 1337 Alaska daylight time, a Beech F-90 King Air, N15, sustained substantial damage during an intentional gear-up landing on runway 14, at Ted Stevens Anchorage International Airport, Anchorage, Alaska. The airplane is owned and operated by the Federal Aviation Administration (FAA), Oklahoma City, Oklahoma, and was being operated as a visual flight rules (VFR) training/proficiency flight under Title 14, CFR Part 91, when the accident occurred. The first pilot, an airline transport pilot/certificated flight instructor, and the second pilot, a commercial pilot receiving proficiency/recurrent training, were not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated at 0945 from the Ted Stevens Anchorage International Airport. During an interview (transcript attached) conducted by the FAA on September 19, 2000, the first pilot reported that he and the second pilot had just completed a missed approach at Soldotna, Alaska, and were transitioning to the instrument landing system (ILS) runway 19R approach at the Kenai, Alaska, municipal airport. He reported that after intercepting the ILS at Kenai, the airplane's landing gear was extended in preparation for the approach. The first pilot reported that the gear extension seemed different from previous extensions, in that the airplane "shuddered" before the landing gear completed the extension cycle, but the three, green, "down and locked" landing gear indicator lights illuminated. The first pilot reported that shortly thereafter, while still on the approach, the airplane's right engine fire extinguisher discharge light illuminated. He reported that they terminated the approach, raised the landing gear, and returned to Anchorage. After arrival in the Anchorage area, the pilots attempted to lower the landing gear via normal extension procedures. The first pilot reported that the indicator light for the right main gear did not illuminate. After confirming that the right main gear was not down, he made numerous attempts to extend the landing gear via normal procedures and manual gear extension procedures, which is accomplished by pumping a ratchet handle which actuates a mechanical chain drive to the gear linkage. After determining that the right main landing gear could not be extended, the first pilot elected to perform a wheels-up landing to runway 14. At 1337, approximately three hours and 45 minutes after the airplane's original departure from Anchorage, the airplane landed wheels-up on runway 14. PERSONNEL INFORMATION The first pilot, who was seated in the right seat, is employed by the Federal Aviation Administration at the Anchorage Flight Standards District Office, as a principal operations inspector. Among other certificates and ratings, the pilot holds an airline transport pilot certificate (ATP) with an airplane multiengine land rating. He also holds a flight instructor certificate with airplane single-engine land, airplane multiengine land, and instrument ratings. At the time of the accident, the pilot held a FAA second-class medical certificate dated November 12, 1999. According to the Pilot/Operator report (NTSB form 6120.1/2) submitted by the operator, the pilot's total flight time in all aircraft was 4,718 hours, of which 236 were accrued in the accident aircraft make and model. The second pilot, who was seated in the left seat, is also employed by the Federal Aviation Administration at the Anchorage Flight Standards District Office, as an Aviation Safety Inspector. He holds a commercial pilot certificate with airplane single-engine land, airplane multiengine land, airplane single-engine sea, airplane multiengine sea, helicopter, and instrument ratings. The second pilot also holds a flight instructor certificate with airplane single-engine land, airplane multiengine land, and instrument ratings. At the time of the accident, the second pilot held a FAA second-class medical certificate dated July 25, 2000. According to the Pilot/Operator report, the second pilot's total flight time in all aircraft was 9,115 hours, of which 76.6 were accrued in the accident aircraft make and model. AIRCRAFT INFORMATION The accident airplane, a Beech F-90 King Air, was issued a normal category standard airworthiness certificate on June 22, 1981. Maintenance records indicated that the airplane's last inspection, a 150-hour primary inspection under an Approved Aircraft Inspection Program, was accomplished on April 10, 2000. The inspection records indicated that the airplane's main landing gear and associated components were inspected, and no mechanical anomalies were noted. At the time of the inspection, the airframe had accrued 5,007.7 hours total time, and 7,706 cycles (each landing represents 1 cycle). At the time of the accident, the aircraft had accumulated approximately 5,112 hours total time, and 8,023 cycles. METEOROLOGICAL INFORMATION The 1353 Aviation Routine Weather Report (METAR) at Anchorage, reported variable winds at 5 knots; visibility 10 statute miles; broken clouds at 5,500 feet AGL; broken clouds at 8,000 feet AGL; broken clouds at 14,000 feet AGL; overcast clouds at 25,000 feet; temperature 12 degrees C; dew point temperature 4 degrees C; altimeter setting 29.68 inches Hg. The 1053 Aviation Routine Weather Report (METAR) at Kenai, reported winds from 190 degrees true at 16 knots, with gusts to 23 knots; visibility 10 statute miles; scattered clouds at 2,300 feet AGL; temperature 10 degrees C; dew point temperature 6 degrees C; altimeter setting 29.68 inches Hg. FLIGHT RECORDERS Cockpit Voice Recorder (CVR) The accident aircraft was equipped with a Universal CVR-30a CVR. The CVR was removed from the airplane and sent to the NTSB CVR Laboratory in Washington, D.C., for readout. The recording begins approximately 9 minutes before the gear up landing. No pertinent information was collected from the CVR recordings (CVR Factual Report attached). Flight Data Recorder (FDR) The airplane was also equipped with a Fairchild F1000 solid state FDR. The unit was removed from the airplane and sent to the NTSB Vehicle Recorders Division in Washington, D.C., for readout and evaluation. Examination of the recorded data (for the time period of the accident to approximately 25 hours prior) revealed that the airplane was operated in a manner consistent with normal airplane operations. The highest vertical acceleration recorded by the accident airplane's FDR was 1.501 G on landing. (FDR Factual Report attached). WRECKAGE AND IMPACT INFORMATION Investigators from the National Transportation Safety Board examined the airplane at the accident site on September 12, 2000. The airplane came to rest aligned with runway heading, near the runway centerline, approximately 1,625 feet beyond the landing threshold of runway 14. Propeller slash marks in the runway asphalt were noted approximately 700-feet beyond the runway threshold. Miscellaneous fragments of fiberglass were scattered between the slash marks and the airplane. The airplane's landing gear and landing gear doors were in the retracted position. The outboard sections of the right flap and left flap were in the down position. The left and right propeller blades were still attached to their respective hub assemblies, and were in the feathered position. Uniform bending and tip curl opposite of propeller rotation was noted. Utilizing a crane, the airplane was hoisted from the runway and the landing gear was manually extended. The airplane was then towed to a hangar located on the airport. TESTS AND RESEARCH On September 13, 2000, investigators from the NTSB and personnel from the FAA, examined the airplane's landing gear system at the FAA maintenance facility in Anchorage. The examination revealed that the right landing gear upper and lower drag leg had separated as a unit from its attach point on the forward wing spar. The support bracket and rib assembly for the drag leg were still attached to the upper drag link. Two longitudinal formers located between the forward and aft spars were buckled. The attach point for the fire discharge annunciator light wire harness, located at the bottom of the fire extinguisher bottle, and adjacent to the outboard longitudinal former, were broken. The mounting bracket for the fire extinguisher bottle was bent. The outboard landing gear door and associated retraction bracket were bent. Black, tire-like, skid marks were noted on the inside surface of the landing gear door. The airplane was placed on jacks and the landing gear was functionally checked. With the airplane connected to a ground power unit, an attempt was made to extend the landing gear. During the extension sequence, it was noted that the right main gear tire jammed on the inside of the outboard landing gear door, preventing the gear from completing its extension cycle. The left main gear and nose gear completed the extension cycle, and the two associated down indication lights illuminated. ADDITIONAL INFORMATION The Safety Board did not retain possession of the airframe, which remained in the operator's hangar after the initial inspection. The cockpit voice recorder and flight data recorder were returned to the FAA in Anchorage, Alaska, on May 16, 2001.
The failure of the right main landing gear drag leg (scissors) attach point, which resulted in the landing gear becoming jammed against the landing gear door during the extension cycle.
Source: NTSB Aviation Accident Database
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