Too Quiet Part 3: "What's That Funny Smell?"

Lighthouse Casablanca, Morocco - photo by JoAnn Sturman

by S.R. Oberst

It was only a few months until my next engine failure. This one occurred while I was flying a functional check flight (FCF) on a helicopter returning from extended maintenance work, including an engine replacement. An FCF ensured that an aircraft was safe and ready to be used on operational missions.

When I first arrived in the unit over four years earlier, all senior pilots in our unit flew FCF missions. Unfortunately, in the post Viet Nam, Jimmy Carter era, Air Force pilots were bailing out of the service quickly. So, except for the Commander and the Operations Officer, I was the next senior pilot with just five years of flying experience. For the last six months in the unit, I was the FCF pilot for most of the flights required by the Chief of Maintenance.

The FCF pilot put the aircraft through various maneuvers depending on what had been done by maintenance. There were a number of power parameters that had to be checked following an engine replacement. After the ground checks of the engine went smoothly, I took off to an open area west of the base that we used for all FCF flights. This area provided an uninhabited area to land should anything go wrong.

One of the stress tests on the engine required putting the helicopter into a climb at maximum continuous power for a period of time. By the time this test was completed I was several thousand feet above the ground. When I lowered the collective at the end of the test, the engine did not react normally. I noticed the engine RPM fluctuated about 200 RPM up and down, while under normal operating conditions it should not fluctuate at all.

I lowered the collective immediately, began a descent, and retarded the engine throttle slightly to keep the engine disengaged from the transmission. If the engine did fail, the helicopter would not lose any rotor speed. Even though the engine had not failed, as a precaution I had the helicopter in autorotation. Due to the high altitude, time was not an issue. At a 1500 foot per minute rate of descent, I had over 3 minutes of preparation time.

I should note that few helicopter pilots practiced high altitude autorotations because it was not a standard training maneuver. Fortunately, I had experimented with dozens of these over the years while flying on many otherwise boring missile support missions. Although a violation of flight regulations, I felt that training for emergencies of all sorts, as well as learning how the helicopter performed, was a smart thing to do. It was a lot of fun flying in ways that stretched the aircraft’s capabilities, but it also made me a better pilot.

After entering the autorotation, I contacted the tower air traffic controller and indicated I was not declaring an emergency, but due to fluctuating engine speed, I was making a precautionary landing. The three minute decent seemed like an eternity, and I wondered if I would land with engine power or have to perform a power off autorotation. I tried to apply fuel using the manual fuel switch, but it had no effect on the fluctuating engine speed. When I started my descent, the helicopter was headed into a 15 knot head wind – perfect conditions for an autorotation. In order to stay positioned for a landing in the field below, I began a slow steady turn to the right. My plan was to turn about 180 degrees and fly away from the field. At about 1,000 feet above the ground I made another 180 degree turn and lined up for a landing into the wind.

The engine RPM was now lower than when I originally retarded the throttle. I still had plenty of time, so I rolled the throttle to full on. The engine did not respond. Now less than 500 feet above the ground, I did not want to risk the chance of the engine suddenly engaging, so I rolled the throttle to idle. The engine was much quieter as I focused on maintaining rotor speed, executed a smooth flare, rotated the helicopter to level 20 feet above the ground, and finally timed the upward pull on the collective to stop the descent and smoothly touchdown at about 5 knots.
Of the three engine failures I experienced, this was by far the simplest one to handle. Although, technically the engine never failed, once on the ground the throttle was not responsive.

Maintenance had to tow the aircraft over 6 miles back to the base. A post incident investigation revealed improperly installed compressor bleed valves. In addition, the fuel control had been incorrectly calibrated. The engine mechanic was once again A1C Potts, who had only recently regained his job status that had been taken away after my previous engine failure. (See The Other Left)

Two months later Airman Potts was arrested following a major drug investigation by the Air Force Office of Special Investigations. Potts was heavily into marijuana, not only smoking it in his dorm room, but distributing it as well. The OSI discovered over 15 kilos in his dorm room and pickup truck. As a routine, Potts worked the second shift and did not come to work until 2:00 PM each day. Apparently he smoked dope in the morning, came to work high, and then worked on helicopter engines. Potts went to a military prison, but not before implicating about a dozen other airmen who also enjoyed getting high in the dorm. Fortunately his weed induced maintenance errors were responsible for only the two engine failures which occurred when I was flying.

Epilogue

Several years later, as a flight evaluator, I was sent to a helicopter unit to give the Detachment Commander, Major Mack Jackson, his annual checkride. (See Ask Me No Questions) Of course, Mack’s autorotations were nearly perfect; however, he struggled with the hydraulics off approach to the extent that I had to take the controls from him and turn the hydraulics back on. “You know,” I said to him, “I never did get to show you how I do a hydraulics off approach when I flew with you that time at Hill AFB years ago, so I’ll take it around and show you one now. Oh, and by the way, before I have you shut off the hydraulic switch, it is this one here,” as I pointed to the switch at the top of the pedestal.

After my last engine failure, I flew another 1,200 hours without another before being assigned to a desk job. All three engine failures had some things in common: I was flying when they occurred, each failure was caused by someone doing something stupid, all on board walked away unharmed, and lastly, it sure gets quiet when the engine quits, perhaps Too Quiet.