Troubleshooting

ARTICLE – [ long title : Troubleshooting and other fun things I did this summer ]

Long-time maintenance professionals carry a virtual encyclopedia of “Tribal Knowledge” between their greying temples. But they’re also experienced enough to know that “Maintenance by Memory Kills” and that Operations and Maintenance manuals are there for a reason.

 

I’M BAAACK!!  Did you miss me? I must admit, I did miss you guys. Sorry I played hooky from our class session last issue. I was going to tell you that the dog ate my article, but even I don’t believe that one.  But I did start a new job that caused some confusion in my schedule. Sorry I was absent, but I am here now, so let’s get to it!

Along with a new gig this summer also brought another birthday. And, along with the fact that the Los Angeles County Fire Helicopter was hovering above the candles on my birthday cake I realized that I have been playing in the helicopter industry for a long time.  I say, “playing” because this has been and continues to be a great career. A big part of the playtime has been troubleshooting engine issues with my fellow helicopter technicians.  Over the last 40 years I have learned some great lessons on troubleshooting that I want to share with you today.  So whaddya say? Time to get started? I believe so.

In all of my conversations with other technicians a couple of things are glaringly obvious, actually four things to be specific:

1. I own all the broken engines. It is true! Because each phone call begins this way: “Your” engine:
a. won’t start
b. starts hot
c. is vibrating like a dog shaking off water
d. just made metal
I never own the good engines.

2. There appears to be big communication gap between us technicians and the helicopter driver (AKA the pilot).

3. The Original Equipment Manufacture’s (OEM) Operations and Maintenance (Ops & Maint) Manuals are not being used effectively or in some cases not at all. At times we use our Tribal Knowledge in place of what is in the Ops & Maint manuals.

4. We all want to start our investigation with the most complicated part of the offending system.
How ‘bout we expand these four points?

1. I own all the broken engines
I know that sounds a bit presumptuous, but it is true. Mostly I believe it is just a technician expressing their frustration over an engine problem that has them temporarily stumped. And I only mention it because I am sure there are other tech reps that hear the same thing. In all cases we are happy to listen and offer suggestions.  Sometimes just discussing the problem with another technician helps solve the issue.

2. The pilots
As technicians one of the best troubleshooting tools we have is our pilot. Who knows the behaviour of the helicopter better than the pilot who has been strapped to that helicopter for two-plus hours? I know that after the helicopter lands the last whining we want to hear is that of the engine as it spools down. However, in order for there to be a smooth operation in our flight department there must be a mutual trust between those who fly and those who fix. The pilots can’t do their job effectively if they are worried about the quality of the maintenance they are flying behind. And we can’t do our job effectively if we don’t listen to and trust what the pilot says during the post-flight conversation. We don’t want to hear: “It’s broke again” any more than they want to hear: “What did you do this time?”

In order for the communication to work it has to be nonjudgmental and open with the mutual goal to solve the problem with the helicopter as soon as possible. Pilots and Mechanics don’t have to be spit-swapping buddies, but we need to respect the other’s skills and knowledge required to accomplish our separate but equally important jobs.

3. The operations and maintenance manuals
Tribal knowledge and “tricks of the trade” can be great information that is shared among us all and is based upon our common experiences. And, truth be known the Engine Manufactures (OEMs) used the tribal knowledge they got and continue to get from us as part of troubleshooting information they have in their Ops & Maint manuals. What the OEMs have done is organize this stuff and then put it in logical progressive order for easy reference. Then they put it all in a cool manual that our companies pay big bucks for.

So what makes the Ops & Maint manuals special? Along with the troubleshooting knowledge you will find:

1. In general, all the facts required for the care and feeding of our turbine engines.
2. The information on component time limits.
3. Which cleaning agents and marking utensils can be used during maintenance.
4. Engine and engine accessories installation instructions.
5. Troubleshooting the most common engine maladies.
6. A brief resume on the operation of the engine and accessories.

So what about this “Tribal Knowledge” that hasn’t made it to the Ops & Maint manual and may not? As we discussed earlier, Tribal Knowledge is what we learn about the engine/helicopter as we go about our day-to-day maintenance duties, and should be used in conjunction with, not instead of, the information in the Ops & Maint manual. Of course, in a lot of cases, Tribal Knowledge is not written down anywhere. Thus, like anything that is passed along verbally, these cool maintenance tidbits can get distorted. And if we rely solely on doing maintenance by what we have heard or because we have “always done things that way” we are heading for some serious trouble.

The accident reports where maintenance was the cause are replete with instances where the maintenance procedure was a deviation from the instructions in the Ops & Maint manual, and anyone who has worked with me knows my maintenance mantra: Maintenance by Memory Kills.

Also, think about what you are signing in the engine logbook: “This inspection was completed in accordance with the instructions in the Engine Manufactures Operation and Maintenance Manual.”

This, my friends, is what we are promising the pilot and confirming with our signatures. So then, Tribal Knowledge is bad? No, it is not, when it is used in the proper context. I will give some examples a little later on.

4. Using the K.I.S. method
What is the K.I.S. method? KEEP IT SIMPLE! When the pilot reports an issue, get all the facts, listen carefully to what they are saying including the flight profile; any unusual instrument readings; if the problem came on suddenly, etc. and, well, you get the point.  Get as much information as you can. This leads to another bit of maintenance advice. We (pilots and technicians) should learn the operational habits of our helicopters when it is running as advertised. For example:

a. Know what the engine idle temp is just before the engine is shut down.
b. Learn the vibration signature of the aircraft when it is on the ground.
c. Know what the oil pressure and the engine torque pressure is at idle.
d. Pay attention to the length of time the engine takes to start and reach idle.
d. Go for a flight with the pilot and learn engine temps during a nomad flight. Feel the vibration signature of the helicopter during this flight.
e. Do a power check.

If you and your pilot both learn how the helicopter behaves when all is operationally good when stuff begins to change or changes suddenly you will have a baseline from which to work. And that is the type of Tribal Knowledge I am talking about: that, when used with the Ops & Maint manual, it will make your job easier and keep your helicopter safe.

About the K.I.S. method

We are all proud of our knowledge, and given the opportunity, we want to demonstrate it. If anyone understands this it is me. However, we have to resist the temptation to go to the most complicated part of the system we are working with and begin the wholesale removal and replacement of parts and components all in the name of “troubleshooting.”  Start with the easiest thing and work logically towards the complicated. Here is an example:

The pilot reports the engine has low power. Get as much info as you can from the pilot about their flight profile. If you know what the last power check was compare them. Next, since turbine engine power is a function of turbine temperature compared to engine torque and outside air temperature, make sure the engine instruments are reporting correctly. Next, check to see if there are any engine air leaks. Next, verify the operation of those engine-mounted components that could have an effect on engine power. By starting with the easiest stuff and working toward the more complicated sections we take the trial and error out of our troubleshooting and get the problem solved quicker.

Conclusion
Let me conclude with a couple of things that have worked well for me:

1.  The pilot reports the sensation of a vibration during flight. You and the pilot     have had a good conversation and he tells you this has been coming on for a while and getting worse. You have noticed that you are replacing engine hardware more frequently.  Also, you have had to replace the light bulbs within the aircraft marking lights or the anti-collision light. With the engine running on the ground you feel a vibration in the sheet metal next to the engine bay. Okay, it is now time to get out the engine vibration analyzer and the Ops & Maint manual and determine which component, engine, main rotor, tail rotor or drive system, is causing this and proceed accordingly.

2.  The pilot reports an engine chip light. Trust me, if you have ever been in a helicopter that had this occur it will get everybody’s attention. Most of the time you will have an excited pilot explaining where they were and what they were doing. Again get as much information as you can. Then as most engines have multiple chip detectors investigate which chip detector attracted the metal.

This will help you possibly determine which bearing or gear within the engine is shedding metal. Remove the metal, refer to the Ops & Maint manual to determine as to what is and what is not acceptable and proceed as directed. It doesn’t take much metal to complete the circuit on the chip plugs.

If the piece of debris can be considered “normal” save it and make a note in the engine logs of the engine time. Then if you get a repeat occurrence you will have a record of what the last metal looked like, and the operating time between occurrences.

Okay, I am sure you get the point. Always keep your line of communication open with the pilot. Determine what has changed operationally from when the engine was working correctly. Small changes are harbingers of larger problems if not caught early. Use the K.I.S. method for troubleshooting. Use the information in the Ops & Maint manual for guidance. And if you get to a point where you want to get another opinion, call your assigned technical representative. Trust me we love to help.  So with that said I will let you all get back to work.

Once again thanks for attending today, and if you have any Tribal Knowledge you want to share send it to Air Maintenance Update. After all isn’t that what this magazine is all about? Take care and remember even the best pilot can’t fly until you say it is okay to fly.