N72VF

HISTORY OF FLIGHT

On December 12, 1997, approximately 2230 Pacific standard time, a Twin Commander (formerly Aero Commander) 690A, N72VF, registered to Yakima Theatres Inc. of Yakima, Washington, collided with terrain while on approach to Yakima Air Terminal, Yakima, Washington. The airplane was destroyed by impact forces and a post-crash fire, and the airplane's private pilot-in-command (a Yakima business owner whose holdings included Yakima Theatres Inc.) and one passenger, the pilot's 16-year-old son, were fatally injured. The 14 CFR 91 personal flight departed Boeing Field, Seattle, Washington, about 2149. An instrument flight rules (IFR) flight plan had been filed for the accident flight, and according to FAA air traffic control (ATC) records, the pilot canceled IFR at 2227, reporting to the Seattle Air Route Traffic Control Center (ARTCC) that he had the destination airport in sight. Night visual meteorological conditions (a 1,500 foot overcast ceiling with 6 statute miles visibility in mist) were reported at Yakima at 2156.

The Yakima air traffic control tower and the local approach control facility (Chinook Approach) close daily at 2200. During the hours that these facilities are closed (2200 to 0600), the airport operates as a non-towered airport within a Class E surface airspace area, and Seattle ARTCC provides ATC services to IFR aircraft operating to the airport. According to the FAA's transcript of communications between Seattle ARTCC and the accident aircraft, Seattle ARTCC issued N72VF a "cleared for approach" clearance to Yakima at 2209:35. According to the FAA Pilot/Controller Glossary, the phraseology "cleared approach" authorizes the pilot to execute any standard or special instrument approach to the airport.

National Track Analysis Program (NTAP) ATC radar data indicated that at 2220:05, approximately 10 minutes after being cleared for approach, N72VF initiated a descending, approximately 270-degree left turn resembling a procedure turn for the Yakima ILS runway 27 approach. The aircraft began this maneuver from a position approximately 13 nautical miles east-southeast of the airport at an altitude of 4,200 feet, and descended to 3,500 feet (the glide slope intercept altitude for the Yakima ILS runway 27 approach) during the turn (the ILS approach procedure specifies a minimum altitude of 4,000 feet until established on the localizer course inbound.) The last recorded ATC radar position of the aircraft, at 2224:16, was approximately on the runway 27 extended centerline, about 9 nautical miles east of the airport, at 3,500 feet. The average track and ground speed between the last two recorded NTAP secondary radar positions of the aircraft (i.e. from 2222:40 to 2224:16) was computed to be approximately 272 degrees magnetic at 131 knots (the runway 27 localizer course is 269 degrees magnetic.)

Approximately 3 minutes after the time at the last recorded radar position, at 2227:02, the pilot reported to ATC: "o k [I]'ve broken out have [Y]akima in sight gonna land [I]'d like to cancel [IFR]." The Seattle ARTCC controller then instructed the pilot to set his transponder to the visual flight rules (VFR) code setting, and approved a frequency change. The last transmission received from the accident aircraft by Seattle ARTCC, at 2227:10, was, "thank you."

The crash was witnessed by several individuals. Broad points of agreement among the witnesses were that the airplane appeared lower than normal for that point on the approach to the airport, that the airplane descended and impacted the ground at a steep angle, and that an explosion or fireball occurred at ground impact. Additionally, some witnesses reported that the airplane went abruptly from a slight descent angle to straight down, or that the airplane pulled up into a steep nose-up pitch attitude then abruptly pitched down to ground impact. Witness estimates of the airplane's initial altitude above the ground ranged from 60 to 400 feet. (NOTE: Based on the published glide slope angle of 3 degrees and threshold crossing height of 58 feet, the ILS glide path at a ground distance of 2.2 nautical miles from the threshold [the approximate distance from the threshold to the crash site] was computed to be 759 feet above touchdown zone elevation.) Additionally, one witness reported he saw a propeller stopped, one witness reported he heard an engine sputtering (but also reported he heard the engines racing immediately before the airplane impacted the ground), and two witnesses (a husband and wife riding in a car approximately 1 mile away from the crash site) reported the airplane appeared to them to be on fire prior to ground impact (the husband stated the airplane initially looked like a "falling star" or meteor, and the wife stated it initially looked like a firework or a flare.)

The accident occurred during the hours of darkness at 46 degrees 33.3 minutes North and 120 degrees 28.8 minutes West.

PERSONNEL INFORMATION

The pilot held a private pilot certificate with airplane single-engine land, airplane multiengine land, and instrument-airplane ratings, and a second class medical certificate issued on September 24, 1996. The medical certificate carried a limitation requiring the wear of corrective lenses while exercising the privileges of the airman certificate.

The pilot completed recurrent training on the Twin Commander 690A at FlightSafety International's Bethany Learning Center, Bethany, Oklahoma, on November 8, 1997, and completed a biennial flight review and instrument competency check in the accident aircraft on November 21, 1997. Noland Decoto Flying Service of Yakima, a fixed-base operator (FBO) which maintained the accident aircraft and one of whose instructors administered the last flight review to the accident pilot, reported that the pilot had over 4,800 hours total time including over 80 hours in the AC-690A.

AIRCRAFT INFORMATION

According to FAA records, Yakima Theatres Inc. became the registered owner of the accident aircraft (a 1975 Twin Commander [formerly Aero Commander] model 690A, serial number 11242) on July 14, 1997, approximately five months before the accident. Noland Decoto reported that the aircraft was configured with two crew and six passenger seats. The aircraft was on a manufacturer's approved inspection program, and received its last inspection in accordance with this program, a 100-hour/periodic inspection performed by Martin Aviation of Santa Ana, California, on April 25, 1997. Noland Decoto reported that the aircraft had been flown 92 hours since this inspection. The airframe total time at the time of the accident was approximately 7,001 hours.

The airplane's two AlliedSignal (formerly Garrett) TPE331-5-251K turboprop engines both had approximately 4,175 hours since overhaul at the time of the accident. Work was accomplished on both engines by Eagle Creek Aviation Services of Indianapolis, Indiana, on February 1, 1993, to allow both engines an extension to 5,400 hours time between overhauls (TBO) in accordance with Garrett Service Bulletin 72-0404. Eagle Creek Aviation Services also performed a hot section inspection on both engines at that time. At the time of this work, both engines were documented as having 3,541.1 hours since overhaul.

Both of the aircraft's Hartzell HC-B3TN-5NL/LT10673 3-bladed propellers were overhauled on July 31, 1997, by Western Aircraft Propeller Service, Inc. of Troutdale, Oregon, and reinstalled on the accident aircraft on August 7, 1997, by Aero Air of Hillsboro, Oregon.

According to documentation in the aircraft records, a reinforcing doubler, manufactured from 1/4 inch 2024-T3 aluminum, was installed on the rear spar of the accident aircraft's vertical stabilizer by Aero Air on August 7, 1997. Documentation of the repair indicated that the doubler was installed due to discovery of a spurious 1/8 inch diameter hole that had been erroneously drilled through the spar cap. An FAA field approval, signed by an FAA designated engineering representative (DER), was obtained for this repair. The repair was accomplished pursuant to engineering report LGK072397, "Fin Spar Repair, Aero Commander 690A, S/N 11242", dated July 23, 1997, prepared by the same FAA DER (DER number NM2520). According to this report, the doubler was to be attached using seven HL20PB-5 "Hi-Lock" fasteners installed through existing 5/32 inch diameter fastener holes in the spar cap, and the doubler and fastener combination was designed to carry the entire structural load of the spar.

All of the airplane's 22 interconnected fuel cells were removed and replaced by Eagle Creek Aviation Services during major maintenance to the aircraft on February 1, 1993, at 6,366.7 hours airframe total time. Aero Air subsequently recorded that it repaired wing fuel leaks in the accident aircraft on August 7, 1997. The repairs consisted of tightening clamps on three left wing fuel cells and one right wing fuel cell, and replacing two right wing fuel cells as well as the upper and lower center fuel cells with new cells. Downtown Airpark, Inc. of Oklahoma City, Oklahoma, subsequently replaced 18 of the aircraft's fuel cells (all except the two left aft inboard and upper and lower center fuel cells, per part numbers referenced in the aircraft log entry) on November 10, 1997, approximately 24 flight hours before the accident.

Downtown Airpark also installed an Apollo 2001 Global Positioning System (GPS) and an S-TEC System 65 two-axis autopilot/flight director system with yaw damper, altitude preselect, and PN-101 horizontal situation indicator (HSI) on November 5, 1997. The Apollo 2001 GPS is certified for non-precision IFR approach operations. The S-TEC System 65 autopilot installation was performed per FAA Supplemental Type Certificate (STC) number SA09013AC-D, issued to S-TEC Corporation of Mineral Wells, Texas. It could not be determined whether or not the GPS or autopilot systems were b...