Fatal ultralight wing separation near Richelieu Airport

Casualties unknown • Saint-Mathias, Quebec, CA

A training flight ended in tragedy when the left wing of an ultralight aircraft detached in mid-air, resulting in two fatalities in the Richelieu River.

What happened

Shortly after departing Richelieu Airport, Quebec, an ultralight aircraft experienced a structural failure while climbing over the Chambly basin. At an altitude of approximately 500 feet, the left wing of the aircraft separated from the fuselage. The aircraft and its two occupants, an instructor and a student pilot, crashed into the Richelieu River. The impact resulted in two fatalities and caused substantial damage to the aircraft. At the time of the accident, weather conditions were clear with visibility exceeding 10 miles and light westerly winds.

The investigation

Investigators examined the aircraft's history and the structural integrity of the wing attachments. The aircraft had been used for pilot training by Aérotech Aviation. While the aircraft was originally purchased unassembled, it had been stored in a hangar since its acquisition, meaning the wings had not been disassembled or reinstalled for some time.

Technical analysis focused on the left wing's rear attachment point. This specific attachment had been previously modified by the original builder using stainless steel brackets to adjust the wing's position. This modification deviated from the manufacturer's original design drawings. Investigators also examined the hardware used to secure the wing, specifically a 5/32-inch aircraft-quality retaining pin and its associated lock ring.

Findings

  • The investigation established that the retaining pin was not secured by a lock ring.
  • Evidence at the attachment point indicated that the pin had been gradually disengaging over the course of several flights.
  • The disengagement of the pin allowed the left wing to twist, which subsequently caused the remaining wing attachment points to fail due to overload.
  • A pre-flight inspection of the left wing attachment was not performed, which would have allowed for the detection of the loose pin.
  • Although the wing attachment had been modified in a manner inconsistent with the designer's specifications, this modification was not determined to be the cause of the separation.

Probable cause

The left wing separated because the retaining pin disengaged during flight because it was not secured with a lock ring, a condition that went undetected due to the lack of a pre-flight inspection of the wing attachment.

Frequently asked questions

What happened in the 1995-05-09 Beaver RX650 C-IDFL accident near Saint-Mathias, Quebec, CA?

A training flight ended in tragedy when the left wing of an ultralight aircraft detached in mid-air, resulting in two fatalities in the Richelieu River.

What aircraft was involved and where did it happen?

The accident on 1995-05-09 involved a Beaver RX650 C-IDFL, operated by Aérotech Aviation, at Saint-Mathias, Quebec, CA.

What was the probable cause of the accident?

The left wing separated because the retaining pin disengaged during flight because it was not secured with a lock ring, a condition that went undetected due to the lack of a pre-flight inspection of the wing attachment.

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