Engine Cowling Detaches During Takeoff of Beechcraft C90A

Casualties unknown • SALVADOR, BA, BR

A Beechcraft C90A experienced the detachment of its right engine's upper cowling during takeoff from Salvador, Brazil, resulting in no injuries.

What happened

On April 30, 2010, a Beechcraft C90A, registration PP-EPS, was performing a takeoff from the Salvador Aerodrome (SBSV) in Bahia, Brazil. The aircraft was operated by the Bahia State Government (Casa Militar) and was carrying two pilots and six passengers.

During the takeoff roll, the upper forward cowling of the right engine became detached. While the co-pilot initially noticed something falling from the engine during the first segment of the takeoff, the crew continued the climb and subsequently performed a checklist, which confirmed the loss of the cowling. Despite the incident, there was no change in engine performance. The pilot elected to return to the aerodrome, landing safely without further complications. All eight occupants were unharmed, and the aircraft sustained only minor damage.

The investigation

CENIPA investigators examined the aircraft' and the maintenance history of the engine cowling fasteners. The investigation focused on the mechanism used to secure the cowling, specifically a hexagonal bolt with a low-relief arrow engraved on its head. This arrow is intended to align with a white mark indicating the "LOCK" position when the fastener is properly secured.

Investigators found that the low-relief engraving made it difficult to visually confirm if the arrow was correctly aligned with the lock mark. It was determined that the fastener likely had not been properly secured following a previous maintenance inspection or service. The vibrations experienced during engine start and the takeoff roll likely caused the unsecured fastener to open, leading to the detachment of the cowling.

Findings

  • The primary contributing factor was that the engine cowling fastener was likely not properly locked following a previous maintenance event.
  • The difficulty in visually verifying the alignment of the low-relief arrow on the bolt head contributed to the possibility of an improper installation.
  • The aircraft was within weight and balance limits, and the crew was fully qualified and experienced for the flight.

Probable cause

The detachment of the right engine cowling was caused by the improper securing of the cowling fastener, likely due to the difficulty in visually verifying the alignment of the low-relief indicator during post-maintenance inspections.

Frequently asked questions

What happened in the 2010-04-30 aircraft accident near SALVADOR, BA, BR?

A Beechcraft C90A experienced the detachment of its right engine's upper cowling during takeoff from Salvador, Brazil, resulting in no injuries.

What aircraft was involved and where did it happen?

The accident on 2010-04-30 involved a aircraft, registration PPEPS, at SALVADOR, BA, BR.

What was the probable cause of the accident?

The detachment of the right engine cowling was caused by the improper securing of the cowling fastener, likely due to the difficulty in visually verifying the alignment of the low-relief indicator during post-maintenance inspections.

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