Canopy door detaches in flight from Sling 4 near Hailsham

Casualties unknown • Near Hailsham, East Sussex, GB

A private flight experienced the loss of a right-hand canopy door mid-flight near East Sussex after the locking mechanism failed to secure the door.

What happened

On 27 July 2017, a Sling 4, registration G-LDSA, was conducting a private flight from Lydd Airport to Shoreham Airport. The aircraft was carrying a pilot and one passenger. Approximately 30 minutes into the journey, while cruising at 2,200 ft with an airspeed of roughly 116 kt, the occupants experienced a sudden surge in wind noise. The passenger noted a blast of air and observed that the upper forward corner of the right canopy door had separated from the fuselage by about 5 cm.

Within 15 to 20 seconds of this initial gap appearing, a loud bang occurred, and the entire canopy assembly departed the aircraft. The pilot notified Shoreham Air Traffic Control and successfully landed the aircraft without further incident. No injuries were reported to the occupants, and no damage to property on the ground occurred. The missing canopy has not been recovered.

The investigation

The Light Aircraft Association (LAA) performed an inspection of the aircraft and consulted the manufacturer. Examination of the fuselage attachment points revealed that both the forward and aft hinges had failed due to overload. While the latch pins remained intact and attached to the fuselage, the canopy itself was unavailable for detailed examination of the locking mechanism.

Although the passenger initially believed the locking lever had remained in the closed position throughout the flight, the investigation established that the canopy could be partially secured even if the lever was not fully engaged in the over-centre position. It remains unclear whether the lever was improperly secured before takeoff or if it was moved during the flight.

Findings

  • The right canopy door detached during flight due to the canopy locking lever not being in the fully closed position.
  • The failure of the hinges was a result of the aerodynamic loads experienced when the door opened.
  • The design of the locking mechanism allows for a partial lock that may appear secure but lacks sufficient strength to resist flight loads.

Safety action

  • The LAA is to issue a safety article to remind pilots to verify that all canopy latches are fully and securely locked before flight.

Probable cause

The canopy door detached because the locking lever was not fully engaged in the over-centre position, allowing the door to open under aerodynamic pressure and subsequently overload the hinges.

Frequently asked questions

What happened in the 2017-07-27 Sling 4 accident near Near Hailsham, East Sussex, GB?

A private flight experienced the loss of a right-hand canopy door mid-flight near East Sussex after the locking mechanism failed to secure the door.

What aircraft was involved and where did it happen?

The accident on 2017-07-27 involved a Sling 4, registration G-LDSA, at Near Hailsham, East Sussex, GB.

What was the probable cause of the accident?

The canopy door detached because the locking lever was not fully engaged in the over-centre position, allowing the door to open under aerodynamic pressure and subsequently overload the hinges.

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