What happened
During a scheduled 14 CFR Part 135 commuter flight, an engine cowling latch disengaged while the aircraft was in cruise flight. This caused the upper cowling to open and separate from the airplane. As wind passed over the open engine compartment, it extracted the engine oil dipstick. Consequently, oil siphoned from the dipstick tube and covered the airplane's windscreen.
The pilot declared an emergency and was joined in-flight by a U.S. Coast Guard helicopter. The helicopter provided guidance to assist the aircraft in reaching a beach for an emergency landing. During the landing sequence, the nose wheel of the aircraft sank into the soft sand, resulting in the nose gear collapse and damage to the airplane's firewall. There were no injuries reported.
The investigation
An inspection of the aircraft was conducted by an FAA aviation safety inspector. The investigation found that the cowling latch receptacles displayed significant wear patterns.