Sikorsky S-76C+ crash near Lagos Lagoon off Oworonshoki, Lagos, Nigeria

The helicopter was returning from the SEDCO Express drilling rig to Lagos when, at 1,000 feet and 120 knots, it pitched up and rolled left, the attitude varying in yaw, roll and pitch for twelve seconds before it struck the water in the Lagos Lagoon off Oworonshoki. Both pilots and four of the ten passengers were killed. There was no fire. The causal factor was separation of the forward servo clevis rod assembly from its bearing and jam nut in the cyclic control system, which left the helicopter uncontrollable. The absence of a secondary mechanical lock in the design of that assembly and wear at the clevis rod end fitting shank, which let the jam nut turn freely under load, were contributory. The Federal Aviation Administration issued emergency airworthiness directive 2015-19-51 on 14 September 2015 requiring a one-off inspection of the main and tail rotor pushrod assemblies and jam nuts and the application of slippage marks.