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Engine Maintenance

warning signs many hours before the date of failure—if the operator has an engine monitor and knows what to look for.

Prop Blade Tip Separation

Partial power loss events are just that—the engine still runs and still makes power but it’s broken and it’s not going to get better without help. Partial power losses call for precautionary landings.

There’s one more emergency—and it may be the scariest of all because of the almost unbelievably violent and destructive vibration that accompanies this emergency. On very rare occasions, a propeller blade tip will break off during flight, causing the whole airplane to shake uncontrollably. The vibration can be severe enough to require repeated attempts to grip the throttle knob to pull back the power.

Sparky Imeson, who recently passed away, was an extremely knowledgeable mountain pilot and author of the Mountain Flying Bible, wrote that, “A precautionary landing is a deliberate, on- or off-airport landing caused by forethought and planning.” In other words, the pilot has a few minutes to survey the possible landing sites, plan the approach to landing, and the luxury of partial power to control the flight path toward the most survivable landing. If we all flew in an ideal world, every engine failure and partial power loss event would happen on a day when the weather is severe-clear and there’s a world-renowned engine repair shop on the airport you can see just off the nose of the airplane. That rarely happens. Partial power loss events can be extremely dangerous if they’re not recognized as true emergencies simply because there’s no way for the operator to determine the extent of the damage, or how many more minutes the engine is going to continue to run.

Safe Not Sorry

These failures can be prevented by conducting a thorough pre-flight inspection of all blades, looking for nicks, gouges, or rock divots. All of these can create stress risers, and must be removed by a qualified technician before resuming flight operations. A prop tip separation is another one of those true emergencies and requires the operator to work through the same checklist of items as a complete engine failure with one exception. Power must be reduced immediately lest the out-of-control forces tear the engine lose from its mounting system.

No one doubts that the best time to look into possible engine problems is when the airplane is on the ground, yet one engine expert, when interviewed for this article, said it like this. “One way of avoiding engine failure is to stop flying an aircraft that has a problem that has not been identified. Used to bug the hell out of me. People would call up and explain an engine problem to me and then say, ‘How about if I fly it up for you to look at?’ Don’t fly an airplane that’s rocking and rolling and you don’t know why.” Good advice, that. Practice loss of power landings and procedures—you probably won’t ever need use your skills but you’ll be glad you did if your flying dice roll out craps. • Plan to survive and fly your plan—your goal is to touch down at the lowest speed possible while still under control of the airplane. • Altitude above the ground is more valuable than a wheelbarrow full of gold. Trade airspeed for altitude in an emergency. • Don’t pass up a suitable landing strip for any reason. If you’re high, lose altitude over the landing area instead of trying to stretch your glide to a more “suitable” landing area or airport. • Decide on a course of action and commit to it. • Take a couple of real deep breaths and get on with it.

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