What happened
On June 14, 2015, a Beechcraft H 750 departed from LFMN (Nice Côte d'Azur Airport). Shortly after takeoff and following the retraction of the landing gear, the crew observed several warning lights, including SQUAT, STALL IDENT, and FDR FAULT.
The flight crew was initially cleared to climb to flight level 160. However, upon reaching flight level 60, the crew identified a loss of cabin pressurization and requested to terminate the climb at flight level 100. Before reaching the requested altitude, a CABIN ALT warning light illuminated.
In response to the pressurization issue, the crew requested a descent and holding instructions. They were assigned vectors and a descent to 4,000 feet, subsequently holding over the NERAS waypoint. The crew remained in a holding pattern for approximately 20 minutes to burn off fuel until the aircraft reached a permissible landing weight. The flight concluded with a routine landing on runway 04.
The investigation
The investigation initially considered that the loss of pressurization might have been caused by a malfunction in one of the weight-on-wheel switches. However, subsequent information provided by the operator revealed a different technical origin for the system failure.
Findings
- The loss of cabin pressurization was caused by poor grounding of the relay box.