Ercoupe (Eng & Research Corp ) 415E N94818

Summary

On 20 March 1999 at about 16:23 local time, a Ercoupe (Eng & Research Corp ) 415E registered N94818 was involved in an accident near Kingman, Arizona, United States. 2 people were on board and 2 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

20 March 1999 at 16:23

Classification

Accident

Location

Kingman, Arizona, United States

Nearest airport

Kingman (IGM)

Coordinates

35.2400, -113.7610

Aircraft

Ercoupe (Eng & Research Corp ) 415E

Registration

N94818

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Lake Havasu Cty → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

LAX99FA128

2 people died.

The in-flight loss of airplane control due to rear wing spar attachment fitting failure. The failure resulted from severe corrosion that was undetected during performance of an inspection specified by an airworthiness directive. The airworthiness directive developed by the FAA was deficient in its specificity relating to recurrence. The directive was also deficient in its procedure requiring external inspection, which would not reveal development of internal corrosion. Contributing factors to the accident were the turbulent atmospheric condition that exacerbated the wing loading and the pilot's operation of the airplane in excess of maximum authorized gross weight.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.