LAX99FA128

A ground-based witness, located north of the airport, reported observing the accident airplane's wings rolling right and left to nearly a vertical bank. Thereafter, the airplane entered a spin and impacted the ground while in a 30- to 45-degree nose low pitch attitude. The impact site was 0.6 miles from the approach end of the runway. Pilots ahead and behind the airplane reported experiencing moderate to extreme turbulence in the traffic pattern. The surface wind was reported at 14 knots with gusts to 22 knots. At the time of the accident the airplane was calculated to be between 94 and 127 pounds over its maximum certificated 1,400 pounds gross weight. During the on scene wreckage examination, the left wing's rear spar attachment fitting was found severely corroded, with missing rivet heads and was separated. Metallurgical examination of the severely corroded spar attachment fitting revealed the presence of rivet heads that had failed and popped off in flight and an associated corrosion-related crack that had compromised the structural integrity of the fitting assembly. Unable to sustain the imposed wing loading, the fitting failed in flight. The failed rivet heads and evidence of the corrosion was on the backside of the spar in an area not visible during inspections. In 1995, a one-time visual inspection of the wings' internal structure for corrosion was mandated by the Federal Aviation Administration through issuance of Airworthiness Directive 94-18-04. This 'one time' visual inspection requirement was complied with according to a logbook entry dated 1997, and thereafter the wings were recovered with fabric. In May 1998, the pilot purchased the airplane, which had been manufactured in 1948. In September 1998, the airplane received another annual inspection during which no logbook entry was made indicating that the wing's internal structure had been reexamined for evidence of corrosion. The corrosion developed due to the presence of moisture and the dissimilar metals (steel bracket riveted to an aluminum spar) being in contact with each other. The severity of the ongoing corrosion process between the metal components would not have been evident during an external visual inspection, despite the fact that a required access panel had not been installed pursuant to the AD. The AD inadequately addressed the aging aircraft issue by indicating compliance could be achieved through performance of a one-time visual inspection to ferret out nonviewable evidence of internal corrosion.

History of flight

On March 20, 1999, at 0923 hours mountain standard time, an Ercoupe 415E, N94818, owned and operated by the pilot, experienced an in-flight structural failure on approach to the Kingman Airport, Kingman, Arizona. Visual meteorological conditions prevailed, and no flight plan was filed. The airplane impacted level, desert terrain and was destroyed. The private pilot and passenger were fatally injured during the personal flight that was performed under 14 CFR Part 91. The flight originated from Lake Havasu City, Arizona, about 0830.

The pilot was a member of the Arizona Ercoupe Group and along with other members, was participating in its annual Wing Ding Fly-in. The initial portion of the flight involved traveling to the Kingman Airport, where breakfast was to be served, and other activities related to the fly-in were planned. The pilot's airplane was refueled, and he was observed to have performed a preflight inspection of his airplane.

Approaching the uncontrolled Kingman Airport, the pilot broadcast his position. He did not indicate that he was experiencing any difficulty controlling the airplane. Within 10 minutes before and after the accident, other pilots in the group also entered the Kingman traffic pattern. They reported to the National Transportation Safety Board investigator that moderate to extreme turbulence was encountered in the pattern. Several pilots also reported experiencing windshear while descending on the base and final approach legs.

A ground-based witness, located north of the airport, reported observing the accident airplane's wings rolling right and left to nearly a vertical bank. Thereafter, as the airplane turned (onto final approach) toward the airport it rolled over, and rotated round and round as it rapidly descended.

Personnel information

Based upon information contained in the pilot's personal flight record logbook, the pilot began receiving flight instruction in 1964. He received a private pilot certificate in 1967. The flight test was performed in an Ercoupe 415-C airplane. Thereafter, the pilot continued flying Ercoupes until July 1969, when he stopped all of his piloting activities. By 1969 he had logged a total of 193 hours.

After a lapse of about 29 years, he resumed flying in June 1998. On June 1 and on October 4 and 6, 1998, the pilot received instruction with a certified flight instructor for a total of 2.7 hours. He passed a biennial flight review on October 6, 1998 in the accident airplane.

Between October 8, 1998, and March 14, 1999, the pilot's logbook indicates he only flew the accident airplane. During this period he made about 64 flights. By March 14, the date of his last logged flight, his total time was approximately 252 hours.

The pilot's wife reported that her husband's flight experience was "limited" with most experience being on local area flights. Her son (the passenger) had not taken flying lessons. He was riding with his father as a passenger as he had on about 10 previous occasions.

Neither the pilot nor son held Federal Aviation Administration (FAA) airframe or powerplant mechanic certificates.

Aircraft information

The airplane was manufactured in 1948. By the accident date, the airframe's approximate total time was 1,887 hours. The pilot purchased the airplane in May 1998.

After undergoing several modifications including installation of a new baggage compartment, seats, instrument panel, avionics, and rudder pedals, the airplane was reweighed in September 1997 and in December 1998. In September and December, its listed empty weight was listed as 1,016 and 983 pounds, respectively. The airplane's maximum certificated gross weight was 1,400 pounds. Accordingly, its useful load was listed as being 384 or 417 pounds.

The last logbook entry referencing the airplane's weight and balance computation indicates its gross empty weight was 1,016 pounds.

Regarding the airplane's loading, information was obtained from a combination of the pilot and passenger's state driver records, a verbal report from the medical examiner, from the pilot's last FAA aviation medical examination, and from fueling records. In addition, the Safety Board investigator made an estimate for the fuel burned off during the accident flight. The calculated total gross weight at the time of the accident was approximately 1,527 pounds (the calculations are appended to this report, see the exhibit for additional details).

The airplane was maintained on a program of annual inspections. Regarding wing-related inspections and maintenance, according to the airplane's logbooks in November 1992, the wing covering was removed. The wings were inspected for corrosion and damage, and then they were recovered.

In 1995, Airworthiness Directive (AD) 94-18-04 became effective. According to this AD, it was issued "to prevent wing damage caused by a corroded wing outer panel structural component, which, if not detected and corrected, could progress to the point of structural failure . . . ."

On October 1, 1997, the airplane received an annual inspection, and on this date a "Major Repair and Alteration, FAA Form 337" was completed. In pertinent part, listed maintenance on this form addressed removal of the airplane's old wing covering and inspection of both wings for corrosion and damage. Thereafter, the wings were again recovered.

The airplane's logbook references work accomplished and states, in part, that new wing attachment hardware was installed. Also, AD 94-18-04 was listed as having been complied with. The airplane engine's recording tachometer was noted at 21.8 hours, and the airplane's total time was listed as 1,815.7 hours.

The last annual inspection was accomplished on September 29, 1998. There was no listing of any maintenance related to repairing damage, or to any inspection of the wing's internal structure. The engine's tachometer was noted at 22 hours, and the total airplane time was 1,816 hours.

Meteorological information

The closest official weather observation station to the accident site was located at the Kingman Airport. In pertinent part, at 0923 Kingman reported clear sky and 10 miles visibility. The surface wind was from 150 degrees at 14 knots, with gusts to 22 knots.

About the time of the accident, several pilots were flying light airplanes in the vicinity of the Kingman Airport. In summary, one pilot reported that he landed on runway 21 about 5 minutes prior to the accident. The pilot stated that he experienced moderate turbulence turning from the base to the final approach legs.

A pilot flying an Ercoupe reported that he had followed the accident airplane in the traffic pattern. The pilot stated that he experienced "extreme turbulence" approaching runway 21.

Another pilot reported that he had been on final approach to runway 21 in an Alon Aircoupe when he overheard the accident pilot announce his position as being on the base leg. The Alon pilot reported that his airplane's wings were "flipping. . . 40 degrees both ways" as he approached the airport, and he experienced "severe turbulence" on the final approach course.

A pilot flying a Piper Cherokee reported that he experienced "severe wind" and turbulence in the traffic pattern. The pilot estimated the wind speed at 40 knots, or greater. The pilot and his passenger observed the accident airplane turn onto the final approach leg. They described the accident airplane's bank angle during its turn as 30 to 45 degrees, or steeper.

A pilot flying a Lucsombe reported that he landed a few minutes after the accident had occurred. This pilot reported experiencing two major wind shifts during his approach. Also, between 1015 and 1030, he observed a large dust devil pass by the airport.

A ground-based witness, who observed the accident airplane descend, reported that while she was driving by the airport her