The pilot, Maj. Elizabeth Kealey, and co-pilot, Capt. Adam Satterfield, were killed in the crash. Both were assigned to Marine Light Attack Squadron 169, and were concluding a short flight from Marine Corps Air Station Camp Pendleton, their home base, to participate in an exercise with the rest of their squadron. Kealey was a captain at the time and Satterfield a first lieutenant — the pair was posthumously promoted during a February ceremony.
Maj. Gen. Michael Rocco, the commanding general of 3rd Marine Aircraft Wing, wrote in his endorsement of the investigation that the deaths of Kealey and Satterfield were "in the line of duty and were not due to their own misconduct."
"There are two errors that contributed to this tragic event. The improper installation of the [main rotor gear box] 40-micron filter cover and the decision by the aircrew to continue flying to the destination instead of landing at a closer suitable area," investigators wrote in an accident report obtained by Marine Corps Times through a Freedom of Information Act request.
"There are two errors that contributed to this tragic event. The improper installation of the [main rotor gear box] 40-micron filter cover and the decision by the aircrew to continue flying to the destination instead of landing at a closer suitable area," investigators wrote.
Instead of putting the aircraft down, they calmly called to have avionics trouble shooters standing by on the flight line.
"This is indicative of a pilot who thinks they have an instrument indication problem, not one that has a full-blown emergency on their hands," the investigating officer wrote.
According to Navy aviation publications, zero oil pressure should trigger pilots to execute "impending [main rotor gear box] failure procedures," under the assumption that the aircraft will soon become inoperable. That means landing as soon as possible.
A maintenance error
The root cause of the trouble with the filter was a maintenance error made long before the accident. The filter housing must be uninstalled to change the filter. But at some point, an unapproved epoxy was used to seal the filter body, preventing Marines from removing it.
After falling vertically and slamming into the ground right-side-up, the aircraft rolled to its right side. Members of Marine Unmanned Aerial Vehicle Squadron 1, working in a hangar about 1,000 feet away, ran to the site and pulled Kealey and Satterfield from the wreckage.
Photo Credit: DoD
As a result, three waivers were issued over months to forgo a filter change. It was deemed unlikely that the filter was dirty, an assumption supported by the post-crash investigation, meaning the filter itself was not a contributing factor.
However, during one failed attempt to change the filter while it was still installed in the aircraft, the cover was damaged. That required that a new one be installed on Jan. 20. Three Marines worked to accomplish the task, which was later inspected and approved by a superior.
But because the filter housing was contained in a small space, they did not realize that a retaining ring that holds the cover on was not seated properly.
Shortly after impact, Kealey and Satterfield were pulled from the aircraft by nearby Marines from Marine Unmanned Aerial Vehicle Squadron 1 who were working in a hangar about 1,000 feet away.
After falling vertically and slamming into the ground right-side-up, the aircraft rolled to its right side. Members of Marine Unmanned Aerial Vehicle Squadron 1, who were working in a hangar about 1,000 feet away, sprang into action.
Ultimately, investigators found "oversights in judgment in various areas that do need to be addressed through mentoring and leadership," however they did not find any negligence.
- Ensuring proper supervision of flightline maintainers removing the 40-micron filter housing.
- Update naval air NAVAIR publications with detailed instructions for removal, disassembly, inspection, reassembly and installation of the filter housing.
- Ensure all members of the UH-1 helicopter community learn pertinent information from the accident and begin training with it pending publication updates.
- Prohibit the installation of the filter cover without removing the entire filter housing.
Beyond that no action was recommended.
"I do not believe there should be any punitive action taken against any members of HMLA-169," the investigating officer wrote.