Structural failure leads to fatal crash of NE-821 in Goiás

Casualties unknown • GUAPÓ, GO, BR

A NE-821 aircraft crashed in Guapó, Brazil, after experiencing in-flight wing separation, resulting in nine fatalities.

What happened

On February 28, 1992, a NE-821 aircraft, operated by M. B. Pereira Comercial Ltda., departed from Brasília destined for Rio Verde, Goiás, carrying two crew members and seven passengers. Approximately fifty minutes into the flight, the aircraft was observed exiting a cloud in an uncontrolled descent. The aircraft struck the ground in Guap and was destroyed by a post-impact fire. All nine occupants perished in the accident.

The investigation

CENIPA investigators examined the wreckage and determined that the aircraft's wings had separated symmetrically near the nacelles. The investigation established that the wings failed due to a positive vertical load overload. Analysis of the wreckage revealed permanent deformations in the wing reinforcement and skin, as well as failures in the spars.

Investigators found that the aircraft was operating with an excess weight of approximately 436 kg. Additionally, the aircraft was equipped with non-homologated fiberglass winglets. While the Carajá (a modification of the PA-31-350) has higher performance and weight than the original design, the investigation noted that the structural safety margin had been reduced during the conversion process. The presence of the unapproved winglets altered the load distribution, increasing stress on the wingtips.

Findings

  • The aircraft suffered a structural failure caused by a positive vertical load exceeding the maximum design limit of 3.43g.
  • The installation of unapproved winglets contributed to increased wing loading and bending stress.
  • The aircraft was operating with an excess weight of 436 kg.
  • The crew lacked significant experience in the Carajá model, with the pilot having only 30 hours of flight time in this specific type.
  • The accident likely involved spatial disorientation while penetrating heavy cumulonimbus clouds, leading to abrupt elevator inputs and exceeding the maximum operating speed (VMO).

Safety action

  • The Department of Civil Aviation (DAC) was tasked with notifying all authorized maintenance workshops that wingtip devices are not approved for this aircraft type.
  • Regional Civil Aviation Agencies (SERAC) were instructed to disseminate the report in lectures and seminars to emphasize the importance of adhering to aircraft operational limits.

Probable cause

The structural failure of the wings was caused by a positive vertical load overload, likely resulting from abrupt control inputs and excessive speed while maneuvering through heavy clouds, exacerbated by the aircraft's excess weight and the installation of unapproved winglets.

Frequently asked questions

What happened in the 1992-02-28 aircraft accident near GUAPÓ, GO, BR?

A NE-821 aircraft crashed in Guapó, Brazil, after experiencing in-flight wing separation, resulting in nine fatalities.

What aircraft was involved and where did it happen?

The accident on 1992-02-28 involved a aircraft, registration PTVLW, at GUAPÓ, GO, BR.

What was the probable cause of the accident?

The structural failure of the wings was caused by a positive vertical load overload, likely resulting from abrupt control inputs and excessive speed while maneuvering through heavy clouds, exacerbated by the aircraft's excess weight and the installation of unapproved winglets.

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