NAME WITHHELD BY REQUEST
It was a typical early summer day at Abu Hammad Air Base, Egypt, located in the Nile Delta northeast of Cairo. I was assigned as an AH-64A maintenance test pilot (MTP) and adviser to the Apache Technical Assistance Field Team. Despite the challenges of English as a second language for my Egyptian counterparts, I thought I had a good handle on how the local pilots expressed themselves. I was wrong.
One of the Egyptian MTPs approached me with a question as I finished meeting with the maintenance squadron commander. He’d been working on a post-phase aircraft for a few days and progressed to track and balance of the rotor system.
“I am hearing a ‘voice’ from the rotor blades,” he said. “Would you fly it with me?”
Thinking the problem was related to an anti-erosion tape issue, I said I would fly with him, and we proceeded to the aircraft. After preflight, he opted to take the front seat to practice running the aircraft vibration analysis kit. I climbed in the back and we progressed through a standard run-up, with everything appearing to operate normally.
After taking our ground and hover measurements, we were cleared for takeoff but elected to remain in the traffic pattern. That wasn’t a huge issue at this location since it was originally a Soviet airbase with a 10,000-foot runway. I didn’t notice anything unusual as we took the measurements at the various airspeeds until I attempted to accelerate to 140 knots for the final measurement. As I approached 100 percent torque, I heard a sound like machine-gun fire coming from the left engine.
Over the din, I heard my front-seater say, “This is the ‘voice’ I was telling you about. What is it?”
I reduced power and, as the torque decreased through about 85 percent, the banging stopped. I croaked out, “Compressor stall,” and made a slow turn to a base leg to set up for landing. Still a bit shaken and hesitant to make any large power changes, I decided to make a roll-on landing — not a huge challenge on a 10,000-foot runway. We landed without incident and returned to the maintenance hangar without further problems.
Lessons learned
So, what did I learn from this incident? More than anything, I learned to not assume anything and to ask questions. Training Circular 1-238, Aircrew Training Manual for Attack Helicopter, AH-64A, Paragraph 6-3b, Crew Coordination Basic Qualities, states the following for accomplishing pre-mission planning and rehearsals: “Pre-mission planning includes all preparatory tasks associated with planning the mission. These tasks include planning for VFR, IFR and terrain flight. They also include assigning crewmember responsibilities and conducting all required briefings and brief-backs. Pre-mission rehearsal involves the crews collectively visualizing and discussing expected and potentially unexpected events for the entire mission. Through this process, all crewmembers think through contingencies and actions for difficult segments or unusual events associated with the mission and develop strategies to cope with those contingencies.”
Had I asked specific questions about the nature of the “voice” he’d heard and the other indications he’d noted, I’d probably been able to decipher the problem before we ever got into the aircraft. At the very least, it would have prepared me for the possibility of what actually occurred.