# NTSB ANC97FA143: Aero Commander AC-500A, N543AN, Ketchikan, AK, September 6, 1997 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: September 6, 1997, 13:00 local (21:00 UTC) - Place: Ketchikan, AK - Coordinates: 55.609573, -131.579071 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=55.6096&lon=-131.5791&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed, report April 15, 1999 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - ADs cited in the narratives: [AD 75-12-09 R2](https://openairdocs.org/ad/75-12-09-R2) (OpenAirDocs) - NTSB case key (mKey): 2941 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC97FA143 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/2941/pdf - Page: https://openairdocs.org/ntsb/ANC97FA143 ## Probable cause The rupture of the right engine fuel supply line as a result of inadequate inspection by the pilot/mechanic, and the pilot's excessive pull up which resulted in exceeding the design stress limits of the airplane. Factors were the improper emergency procedures and failure to feather the propeller. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, cruise - fuel system,line - ruptured (cause) - maintenance,inspection - inadequate, owner/pilot mechanic (cause) - emergency procedure - improper, pilot in command (contributing factor) - propeller feathering - not performed, pilot in command (contributing factor) - Abrupt maneuver, cruise - pull-up - excessive, pilot in command (cause) - Airframe/component/system failure/malfunction, cruise - wing,wing rib - buckled - design stress limits of aircraft - exceeded, pilot in command (cause) - In flight collision with terrain/water, descent - uncontrolled ## Analysis The aircraft had an in-flight breakup when the left wing and tail section separated. Postaccident inspection revealed a right engine main fuel supply line progressive rupture, only trace amounts of fuel in the fuel lines, and no rotational damage to the right engine. Preaccident, long term, fuel leak evidence surrounded the ruptured line. The right propeller was not feathered. The left wing D-tube rib at station 127 exhibited compressive buckling. Left wing fractures were upward, and horizontal stabilizer deformation was downward. During an actual loss of engine power in the airplane 17 months before this accident, the pilot had feathered the incorrect propeller. Both a mechanic, and an FAA safety counselor, who were familiar with the pilot, described him as able to be disoriented, and reliant on GPS for navigation. He had stated five months before the accident that he did not feel his instrument flying skills were proficient, and desired training. On the day of the accident, weather was visual meteorological conditions, with layered clouds above 2,200 feet mean sea level. The pilot stated to the FAA weather briefer that he wanted to make the flight under visual conditions. The flight route and altitude was unknown. ## Factual narrative HISTORY OF FLIGHT On September 6, 1997, about 1300 Alaska daylight time, a Twin Commander AC-500A airplane, N543AN, was destroyed when it impacted mountainous terrain about twenty-eight miles north of Ketchikan, Alaska. The private pilot and the sole passenger sustained fatal injuries. The flight was conducted under 14 CFR Part 91 as a personal flight from Wrangell, Alaska, to Everett, Washington. Visual meteorological conditions prevailed in the general vicinity of the accident site, and no flight plan was filed. The airplane departed Wrangell between 1200 and 1300. Cruise altitude of the airplane, and the intended route of flight is unknown. There are no known witnesses to the accident. The exact purpose of the flight is unknown. The sole passenger was the pilot's wife. She was seated in the aft cabin seat. Acquaintances of the couple stated to the NTSB investigator that she regularly would fly with her husband, and preferred to sit in this location. Located with her was their dog. DAMAGE TO AIRCRAFT The airplane came to rest with the main fuselage, right wing, and both engines, approximately 2,000 feet from the tail section. The outboard 129 inches of the left wing was not located. Several small, light, sheet metal pieces were located downwind of the tail section. PERSONNEL INFORMATION The 81-year-old pilot held a private pilot certificate with airplane, single and multiengine, land and sea, and instrument ratings. His original private pilot certificate was issued on August 30, 1945, with an airplane-single engine rating. He obtained a multiengine rating on July 10, 1961, and an instrument rating on August 23, 1967. He also held aircraft and engine mechanic certificates initially issued November 12, 1941. According to friends, and the mechanic who assisted him with the most recent annual inspection, he occasionally performed his own airplane maintenance. The pilot held a Third Class medical certificate, issued on August 29, 1997, with the restrictions of having glasses available for near vision. On April 2, 1996, the pilot was involved in an accident with the same airplane. During this accident, the airplane sustained a loss of engine power of the right engine. While conducting the emergency procedures, the pilot feathered the left (incorrect) engine. The airplane was then landed at an off airport location and received substantial damage. On July 15, 1996, he was reexamined by an FAA inspector and successfully completed a competency check flight. A general aviation, FAA designated, safety counselor familiar with the pilot, was interviewed by the NTSB investigator after the accident. This counselor stated that in April 1997 he had met with the pilot, who indicated he did not feel his instrument flying skills were proficient, and that he desired to receive some training and practice. This counselor observed the pilot make several small mistakes while preparing to depart on a flight. These were specifically, cross threading an oil cap, starting an engine with a boost pump on which resulted in a flooded start, and stalling an engine during the preflight check. The counselor indicated that there was "room for disorientation with this pilot." A mechanic who flew with the pilot on September 3, 1997, stated that the pilot became disoriented, and relied heavily on GPS for navigation. AIRCRAFT INFORMATION The airplane was powered by two 260 horsepower reciprocating engines. Both engines were overhauled and replaced on June 7, 1996, after the April 2, 1996, emergency landing. This was 37 hours prior to the accident. The airplane last received an annual inspection on May 10, 1997, 19 hours prior to the accident. The pilot/owner performed some of the maintenance, while a contracted mechanic who held an Inspection Authorization (IA), inspected the pilot's work. Three days prior to the flight, both engine driven hydraulic pumps were replaced by the owner. At completion of the pump replacement, the pilot and an IA mechanic flew the airplane. The IA stated during an interview with the FAA that the airplane flew smoothly. Inspection of the wreckage confirmed that all structural wing Airworthiness Directives (AD) had been complied with. AD 75-12-09 R2, for installing an elevator "Bob Weight" into the flight control system to prevent inadvertent pilot induced structural failure, had been installed. The airplane weight and balance at the time of the accident was calculated to be within limits. The mechanic who had assisted the pilot with the last annual inspection stated to an FAA inspector that the pilot had occasionally complained of a fuel smell in the airplane. METEOROLOGICAL INFORMATION Weather reports from the surrounding stations indicated ceilings varying from 2,200 feet to 5,500 feet, with higher layers. The nearest weather reporting station to the accident site was Ketchikan. At 1200, Ketchikan weather was reported to be variable winds at 4 knots, 10 miles visibility in rain, scattered clouds at 1,100 feet, broken clouds at 2,200 feet, and overcast clouds at 3,000 feet. Various pilots interviewed by the NTSB investigator-in-charge reported that ceilings in the areas surrounding the large island where the accident occurred were layered. The ceilings described varied from 2,000 feet to 4,000 feet, with higher layers above. AIDS TO NAVIGATION Navigational equipment in the airplane consisted of VOR, DME, and ADF radio receivers. The mechanic who recently flew with the pilot, told an FAA inspector that the pilot relied on his handheld Global Positioning System (GPS) receiver for navigation information. COMMUNICATIONS No record of in-flight ATC communication was found. No radar coverage exists in the area surrounding the accident site. The pilot received a weather briefing at 1930 on September 5, from the FAA Juneau, Alaska, Flight Service Station. A review of the transcripts of the weather briefings received reveal the pilot stated he wanted to travel VFR to Paine Field in Everett, Washington. The forecast he received called for VFR conditions, and marginal VFR conditions in showers, between Wrangell and Paine Field. At 1021 on September 6, the pilot received another weather brief. He stated, "I'd like to fly VFR from Wrangell to Paine Field." At the time of the brief, the Wrangell weather was IFR. Ketchikan weather was VFR with 6 miles visibility in rain, scattered clouds at 1,200 feet, and broken clouds at 2,300 feet. The pilot did not request or receive the Area Forecast for Southern SE Alaska. WRECKAGE AND IMPACT INFORMATION The fuselage, with both engines and the right wing attached, came to rest about 1,522 feet msl in position 55-44.51 degrees north latitude, 131-25.00 degrees west longitude. The nose was pointing 210 degrees magnetic. The terrain consisted of a 30 degree slope, heavily timbered with numerous 200 feet tall spruce trees. The fuselage came to rest at the bottom of a large tree. Scrape marks exposing fresh wood were visible along the entire length of this tree. No surrounding trees appeared to have damage. The tail section of the airplane, aft of fuselage station 252, was located about 2,000 feet to the east-northeast of the main fuselage. All longerons and rivet lines were deformed in a direction consistent with the tail separating in an aft and right direction. A section of left wing leading edge skin from wing station 98 to wing station 145 was recovered approximately 600 yards northeast of the main fuselage. This section included the leading edge rib at wing station 127. This rib exhibited compressive buckling. The attached upper wing surface sustained compressive buckling. The outboard ends of this section displayed no indications of impact damage from contacting terrain. Several pieces of light debris were located about 200 yards further north of the tail. The 129 inc ## Aircraft - Registration: [N543AN](https://openairdocs.org/deregistered/N543AN-1998-06-18), registration cancelled 1998-06-18, S/N 500A90817 (OpenAirDocs) - Reported make and model: Aero Commander AC-500A - Registry model: [Aero Commander 500-A](https://openairdocs.org/model/aero-commander-500-a) (registry code 0141104) (OpenAirDocs) - Category: Airplane - Serial number: 500A-908-17 - Airframe hours: 6679 - Engines: Continental IO-470-M 260 horsepower reciprocating - Damage: Destroyed - Flight: Personal, Part 91 - Registered owner: Robert Kirke Dent - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 10, 1997, 18 hours before - Departed: WRG, WRANGELL, AK - Destination: PAE, EVERETT, WA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 81; private; airplane ratings: multi-engine land, single-engine land, multi-engine sea, single-engine sea; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 2,577 total, 81 in this make and model, 2,577 as pilot in command, 17 in the last 90 days, 8 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: 1,300 ft broken - Temperature: 52 °F, dew point 48 °F - Altimeter: 29.00 inHg - Observed at: KTN, 28 nm away ## 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 19970906025549A](https://openairdocs.org/incident/19970906025549A), Sep 6, 1997: Gulstm 500A, Ketchikan, AK, Destroyed, 2 fatal. Aircraft broke up in flight. Cause of breakup begin investigated. (From .4) the aircraft had an in-flight breakup when the left wing and tail section… 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.