Jorge Yepiz

As a Flight Instructor I’ve simulated many abnormal conditions in flight, both in training students and training myself.  Being conducted in a relatively controlled environment I always have the comfort of knowing which abnormal will occur and when.  These usually consist of power loss, fire, electrical failure or flight instrument malfunction as required by the PTS; of course any number of things can go wrong in an airplane and it would be impossible to cover every one during training and many have no way of being safely simulated.  The chance to experience an actual abnormal during flight with a student on board is a teaching opportunity I thought I’d never get.

Most common emergency situations have obvious indications.  Loss of power: no sound, plane descends.  Fire: smoke.  Electrical failure: nothing works.  Troubleshooting and resolving is straight forward.  Loss of power: check fuel, fire and air.  Fire: eliminate the fuel source and create an incombustible mixture.  Electrical failure:  is this really an emergency?  The airplane is still flying isn’t it?  More of an inconvenience if you ask me.  Recently, I experienced a rough running engine shortly after takeoff.

The rough running engine scenario is one of those that can’t be simulated.  Not quite a complete loss of power but an urgent situation nevertheless.  The causes are many.  Fouled spark plugs, incorrect fuel/air mixture, vapor lock, carburetor icing, fuel contamination or a structural failure of the engine (e.g. cracked cylinder head.)  Fortunately most of these come up often enough during day-to-day operations that most students get the opportunity to experience them and can be taught how to deal with them.  Fouled plugs can be cleared, a check of the mixture position after descending from 10,000 ft is an easy fix, a bouncing fuel flow needle (indicating vapor lock) can be fixed with an extra push from the aux fuel pump, and carb icing can most often be managed even after forming.  But how would you know if a fuel injector became clogged?  Cutting off or restricting fuel flow to only one cylinder would effectively render that cylinder dead.  The issue here, if you’re unaware of how your gauges work, is that the indications are not what common sense would dictate.  One would initially assume that if fuel flow was reduced into one cylinder the gauge would show a reduced fuel flow as well.  The opposite is true.

The fuel flow gauge is actually a pressure gauge at the flow divider.  A second pressure reading isn’t of much use to a pilot in the cockpit but knowing the rate of fuel consumption is very useful.  When everything is working normally, the flow in the system is proportional to the pressure therefore the gauge face can be marked in gph instead of psi.  When an injector becomes blocked the fuel flow backs up and the pressure at the flow divider increases.  You can figure out what happens next.  Fuel flow indication is higher than normal.  One’s initial reaction would be to lean the mixture but this could only make a bad situation worse.

Thankfully when this happened to me training kicked in.  I had researched this with a fellow instructor after he experienced a similar incident so I immediately recognized what was going on and turned the airplane for landing.  There isn’t much a pilot can do to fix this in flight.  Fortunately we had just departed.  As I reduced power for landing things actually returned to normal however on taxi back to parking it felt as though the engine was trying to break itself off its mounts.  Check out this short video clip of the engine sound during taxi.

Please leave comments.  Share stories or add anything I may have missed.

One of my unspoken resolutions this year is to write about more of my experiences; it’s why I started this blog in the first place.  This year will bring about a career change; from flight instructor to First Officer.  I’m looking forward to documenting my journey.  Step one has begun; my resume is out.  I’ve had the good fortune of meeting some great people and establishing lasting relationships over the past few years.  These friends and coworkers have become an invaluable network that I’ve been able to rely on for guidance.  I am often overwhelmed by others willingness to help.  I hope for the chance to pay it forward someday.

Now I wait.  Wait for what seems like an eternity for the phone to ring.  I know it will, I’ve seen two friends hired recently.  Both reported positive experiences.  I wonder what mine will be?  Time will tell and I’ll write about it here.  In the meantime, I continue to teach.  My opportunity to do what I never imagined just a few short years ago; to give someone the gift of flight.  This has been one of the most rewarding experiences of my life.  Part of me will miss it, but I can’t help hoping the next step comes soon.