N5174D

HISTORY OF FLIGHT

On February 19, 1999, at 1652 hours Pacific standard time, a Cessna 172N, N5174D, made an emergency landing at the El Monte, California, airport, after experiencing an in-flight cockpit fire. The aircraft was destroyed in the subsequent ground fire following the landing. The commercial pilot was not injured. The news reporter/passenger was treated for smoke inhalation at a local hospital and released the same night. An airport employee who responded to the burning aircraft and attempted to extinguish the fire was also treated and released for smoke inhalation. The flight was conducted under 14 CFR Part 91 by Jetcopters, Inc., as a traffic aerial observation flight for a local radio station and originated at the Van Nuys, California, airport, about 1600. Visual meteorological conditions prevailed and no flight plan was filed.

The pilot was interviewed on the night of the accident by Safety Board investigators and the reporter was interviewed several days afterward.

The pilot reported that they were orbiting over a traffic accident about 1/2-mile from the El Monte Airport. The pilot was in the right seat and the reporter was in the left seat. The reporter was reaching behind in the back seat area and grabbed the left doorpost with her hand for support. A "pop" noise was heard. Almost immediately, flames shot out from both sides of the Royalite molding covering the left doorpost at the level of the map light-mounting fixture. The pilot reported that black smoke filled the cockpit. He removed his shirt and attempted to suppress the fire, but was unsuccessful. According to the pilot and the reporter, each time the flames were smothered, they came right back and seemed to grow more intense. The reporter then moved to the back seat to escape the flames. The pilot declared an emergency with the El Monte Air Traffic Control Tower and set up for a downwind landing on runway 1.

Both occupants said that during the time interval that the pilot maneuvered the aircraft into alignment with the runway and landed, the flames had progressed down the Royalite doorpost covering and spread to the left side cockpit sidewall upholstery and the left side of the cockpit glareshield/instrument panel. As the airplane was rolling to a stop, the reporter exited the right side door, followed immediately by the pilot.

Review of video news footage taken by another station's helicopter, which was covering the same traffic accident, showed that about 1 minute elapsed between the airplane coming to a stop and the cockpit being fully involved in flames.

Both the pilot and the reporter stated that they had not noticed any unusual fuel or electrical odors either during this flight or any of the flights in the days preceding the day of the accident.

PERSONNEL INFORMATION

Review of the Federal Aviation Administration (FAA) Airman record files disclosed that the pilot held a commercial pilot certificate with airplane ratings for single engine land, multiengine land and instruments. He also held a certified flight instructor certificate for airplanes. The most recent first-class medical certificate was issued without limitations on April 30, 1998. According to the pilot's logbooks, he had a total time of 1,050 hours. The pilot had been employed with Jetcopters, Inc., for about 1 year and principally flew traffic watch flights for the operator.

The reporter was employed by Shadow Broadcasting Services as a broadcast traffic reporter, and had flown in single engine airplanes on a daily basis covering road traffic conditions for a local radio station.

AIRCRAFT INFORMATION

Review of Cessna Aircraft manufacturing records disclosed that the aircraft was manufactured in February 1979 as a Cessna 172N model, serial number 17272439. Jet Copters, Inc., purchased the airplane in June 1998 for principal use in traffic watch reporting flights. According to the aircraft maintenance records, it had accumulated a total time in service of 8,141 hours. The last annual inspection was performed on June 24, 1998, during the purchase process. The most recent 100-hour inspection was accomplished by Jet Copters, Inc., maintenance department on February 17, 1999, 47 hours prior to the accident.

The airplane was equipped with a factory installed map light mounted about midway down the left doorpost with it's associated switch mounted about 6-inches lower on the post.

Airworthiness Directive (AD) 80-04-08, became effective on February 16, 1980, and was applicable to the accident aircraft by serial number. The AD stated that compliance was to "preclude the possibility of a fuel leak or an in-flight fire due to contact between a map light switch and an adjacent fuel line . . ." and required a one-time inspection of the left doorpost area and accomplishment of Cessna Service Information Letter SE80-3. The pertinent provisions of the AD and Service letter directed a visual inspection of the metal fuel line and map light switch located in the left hand forward doorpost for chafing or arcing, and to provide at least 0.50-inch clearance between the map light switch and the fuel line in accordance with procedures in FAA Advisory Circular 43.13-1A. It also required the installation of a nomex cover (insulator), Cessna Part Number 0511080-1, over the electrical terminals on the rear of the map light switch.

Cessna Service Information Letter SE80-3, dated January 21, 1980, indicated that a protective Nomex insulator on the rear of the doorpost map light switch would be installed on production aircraft from that date forward. It stated that the switch insulator would provide "improved coverage over the switch terminals." The AD and Service Information Letter are appended to this file.

The accident aircraft's maintenance records were examined for evidence of compliance with the AD and the Service Information Letter. In the AD Compliance Section of the first airframe logbook, both AD 80-04-08 and SIL80-3 were noted as complied with, though no date of compliance was recorded. The maintenance entries in the airframe logbook were examined from January 1980 forward, and no entries were found which specifically noted either the AD compliance by name or the work which could be associated with compliance. The entry in the AD compliance section was observed to be in the correct date sequence when compared to the dates of other entries.

A certified copy of the aircraft file was obtained from the FAA Aircraft Registry in Oklahoma City, Oklahoma, for review of FAA Form 337's. In addition, the FAA Form 337's in the aircraft maintenance records were examined to determine the modification history of the airplane as it related to the fuel or electrical system. No modifications or alterations to the airframe fuel system were found. Two FAA Form 337's were found, which detailed modifications to the electrical system in order to plug in and operate a portable AM broadcast radio for traffic reporting purposes. Review of the written installation descriptions and the electrical schematics attached to the Form 337's revealed no common connection between the installed circuits and the circuits routed in the left forward doorpost beyond the common connection to the main electrical power distribution bus.

The operator reported that discrepancies and squawks are reported verbally by the pilots to the maintenance personnel, and no written records are kept. Interviews with company maintenance personnel disclosed that on February 16, 1999, one of the pilots informed the shop that the map light was inoperative in the accident airplane.

Subsequent maintenance records reviews and interviews established that on February 17, 1999, one of the mechanics removed the Royalite doorpost covering and examined the map light area to try to determine why it was inoperative. The mechanic who performed the work reported that he found the washer for the map light mounting post on the cabin floor, so he reinstalled a washer and a nut on the map light post. He further stated that one of the wires between the map light and the switch was disconnected from the switch terminal and he determined that was the reason for the inoperative light. He reconnected the wire and secured the panel. The mechanic tested the light on the ground, found it to be working, and returned the airplane to service.

The mechanic who performed the map light work was interviewed by Safety Board investigators on two separate occasions; by telephone on February 22 and in person on February 24. During the interviews, the investigators were aware of AD 80-04-08 and Cessna SIL 80-3, but asked non-leading general questions concerning what he observed behind the Royalite covering. The mechanic was asked if he recalled anything being behind the map light switch. He responded that he remembered nothing being behind the switch. In response to other questions about the general area condition he stated that he was focused on the map light post, switch, and their associated wiring, and did not specifically look at anything else; however, he did state that there was nothing unusual about the area which attracted his attention, to include fuel like odors. He did not recall whether he observed nylon "V" shaped spacers between the fuel line and the wiring circuits routed up the doorpost.

During the in-person interview, the mechanic volunteered that he had reviewed the parts manual and AD 80-04-08 after the telephone interview. He stated that he definitely reinstalled the Nomex cover over the rear of the map light switch as depicted in the AD.

At the request of Safety Board investigators, Cessna Aircraft provided proprietary drawings and production process specifications covering the design history and configuration details of doorpost area. Review of this data found that in models prior to the 172N (1976 and before), each wing fuel tank had only one supply line, which was routed down the aft doo...