A too-fast rotor and an electrical malfunction are to blame for two Marine Corps helicopter emergency landings that happened within three days of each other on Okinawa, Marine officials said.
The two incidents involved a UH-1Y Huey belonging to 1st Marine Aircraft Wing, which put down on a beach on Ikei Island off the coast of Okinawa on Jan. 6, and an AH-1Z Cobra belonging to Marine Medium Tiltrotor Squadron 265, from the 31st Marine Expeditionary Unit, that landed near Cape Zanpa, on Okinawa's southwestern side.
In both cases, the aircraft and pilots were unharmed and there were no injuries to private or municipal property.
The incidents are inconvenient, however, because some Okinawans have long been leery of Marine aircraft flying over civilian neighborhoods and communities, and the threat that potential mishaps pose to people and property.
In the case of the Huey's emergency landing, officials said in a statement that the helicopter crew saw indications that the main rotor was moving "at too high a speed" while the aircraft executed a scheduled flight off the Okinawa coast.
"In this case, the aircraft performed as designed, the aircrew performed as trained, and there were no injuries to personnel, nor was there damage to property," officials with III Marine Expeditionary Force said in a statement. "... We care deeply for the safety of both our pilots and crew in our aircraft as well as the communities around which we operate."
Regarding Monday's incident with the Cobra, officials said repairs were required following the precautionary landing.
"During a regularly scheduled flight on Monday, pilots received a cockpit indicator warning and followed published procedures to land the aircraft as quickly and safely as possible," officials said. "They chose to land the aircraft as far away from buildings and people as possible."
The problem was a "minor electrical malfunction," officials said. Marines were sent to the landing site to conduct maintenance, and ultimately a sensor located near the tail rotor was replaced. After it was inspected and tests showed no mechanical or structural issues, the Cobra flew back to Marine Corps Air Station Futenma, officials said.
In the case of the Huey landing, the Marine Corps is still investigating the cause of the incident, officials said.
The two emergency landings come less than a month after a window fell off a CH-53E Super Stallion helicopter and landed in an athletic field near a Futenma elementary school Dec. 18, resulting in minor injuries to a young boy.
That incident was determined to be the result of human error, and III MEF announced new training and aircraft inspection efforts to prevent future mishaps.