What happened
On 24 May 2004, an L-39 Albatros (registration ES-YLL) was performing a ferry flight from Den Helder Airport to Groningen Airport Eelde. The aircraft, owned by a Dutch company and hired by the Royal Navy for a military exercise, was carrying a pilot and one passenger. Prior to departure, the pilot placed luggage in the aircraft's nose compartment, a space originally designed for military equipment rather than passenger baggage.
Shortly after departing from runway 22, the pilot observed an object flying past the cockpit, followed by a loud thump and a sensation of a compressor stall in the engine. The pilot noticed that the right-hand hatch of the nose compartment was ajar and saw an object fall from it. Realizing the remaining runway length was insufficient to stop safely, the pilot attempted an emergency landing on the same runway. Despite heavy braking, the aircraft overran the runway, crossed the threshold, and traveled through two ditches before coming to a halt in a field of flower bulbs. There were no injuries to the occupants, but the aircraft sustained serious damage.
The investigation
The investigation focused on the nose compartment's design and the security of its access panels. These panels are held in place by quick-release locking screws that require a quarter turn to secure. The investigation found that while the pilot believed the screws were fully tightened, the right-hand hatch had not been properly closed.
It was determined that the locking mechanism can be deceptive; the screws can be turned a quarter turn without actually falling into their recesses, creating a false sense of security. The investigation also revealed that the space used for luggage was not intended for such use according to Estonian aviation authorities. Furthermore, the aircraft was under Estonian supervision rather than Dutch oversight, as it was not on the Dutch aircraft register.
Findings
- The primary cause of the engine failure was that the right-hand hatch was not properly shut.
- An item of clothing (a coat) was sucked from the nose compartment into the right-hand air intake, partially obstructing the compressor.
- The pilot's method of verifying the hatch was closed relied on the resistance of the screws rather than a manual physical check of the hatch itself.
- The use of an equipment compartment for luggage storage contributed to the incident.
- The aircraft's overrun was caused by the insufficient runway length available for an emergency stop following the engine malfunction.