What happened
On 22 October 2002, a modified Sikorsky S76A, registration G-BMAL, was conducting a short positioning flight between offshore rigs in the southern North Sea. The flight took place during twilight hours under conditions of intermittent rain. Due to the wind direction, the co-pilot was operating the controls from the left seat to manage the approach to the Leman 27 Charlie platform.
While the forward windscreen remained clear, misting on the chin windows obscured part of the view. The co-pilot aimed for the center of the helideck's marked circle. Although the captain lost visual contact with the landing area during the final 100 feet of the descent, the landing itself appeared uneventful to the crew. However, following touchdown, the Helideck Landing Officer informed the crew that the Automatic Deployable Emergency Locator Transmitter (ADELT) located on the rear fuselage had been damaged. Upon inspection, the captain found a fracture in the ADELT housing neck. While the crew was initially unaware of any impact, witnesses later confirmed that the ADELT had struck the edge of the helideck during the landing sequence.
The investigation
An investigation conducted by the operator determined that the ADELT had made contact with the deck-edge safety netting and subsequently hit a cable tray. This cable tray, which protrudes approximately 5 inches above the helideck surface, showed evidence of a dent. The investigation established that the aircraft had crossed the helideck below the required safe profile. This was attributed to either an approach that was too shallow with insufficient flare, or a standard approach that utilized an excessively hard flare.
Findings
- The primary cause of the incident was the aircraft flying below the safe profile during the landing.
- A contributing factor was the aircraft's center of gravity, which was positioned at 80% of the aft limit, necessitating a higher-than-normal nose attitude during the flare.
- The misting of the chin windows may have impacted visibility during the final stages of the approach.
Safety action
- It was recommended that non-handling pilots notify the handling pilot if the aircraft maintains a nose-up attitude of 10 degrees or more when within 30 feet of the surface.
- A review of the approach aiming point was suggested, noting that other aircraft in the fleet target the far side of the landing circle.
- The investigation suggested investigating solutions for chin window misting and considering a modification to relocate the ADELT from the tail area to the right side of the fuselage.