Turbine Technology
Taking a focused approach to fixing discrepancies
By Joe Escobar
Good troubleshooting techniques are essential to being a top-notch mechanic. A mechanic who knows how to effectively troubleshoot a problem is a valuable asset to the company. We will take a look at some keys to effective troubleshooting as well as a new online tool from Honeywell to aid in the troubleshooting process on TFE731 engines.
Where to start?
First in the troubleshooting process is making sure you understand the write-up. Clear communication is essential. Make sure to ask questions if you are unsure about the discrepancy. In fact, the logical steps presented in many troubleshooting charts usually require answering yes/no questions. For example, if looking at a fuel indicator problem, the manual may ask “were there any fluctuations?” In order to proceed, you need to know the answer. A good debrief with the person writing up the discrepancy is always a good idea, especially on discrepancies involving engine rigging or operation. Some typical questions to keep in mind can be:
What altitude was the aircraft at?
Was this an intermittent problem?
What was the flight profile when it happened?
Break it down into pieces
A good troubleshooter is able to look at the problem and break it down into smaller steps, isolating one system or unit at a time until the faulty component is found. This can be a tedious process, but it is essential. Dan Wieprecht, a propulsion engineer with Garrett Aviation explains. “Unfortunately, there are some mechanics out there that take a ‘shotgun approach’ when troubleshooting. They get to a point in the process and change out several components that could be the cause of the problem. This causes the company a lot of unnecessary money.”
Using a shotgun approach is indeed costly. For example, if five components are removed and only one of them is the culprit, you don’t know which one was actually causing the problem. The next time that discrepancy comes up, you will be stuck in the same situation without knowing the true solution. Also, items that are sent in simply tagged as “inop” have to be checked by the repair shop. The time it takes to inspect and test a good component costs money. Add to that the shipping costs, and these parts add up to a lot of money. In these times of watching the bottom line closely this is an undesirable approach to have.
Take a focused approach
When troubleshooting a discrepancy, you are approaching a problem that you don’t know the solution to, using information and testing equipment available to inspect the system, and solving the problem. It is a logical process that involves a planned out game plan. Just as you wouldn’t want a shop mechanic to change out the engine in your car to only find out later that it was just out of gas, the owners are expecting us to fix the problems on their engines in a focused manner without wasting valuable resources.
Many times maintenance manuals offer specific troubleshooting trees for major systems. If not, then it is up to you to develop a game plan to attack the problem in a sequence that will enable you to find the solution.
Know all the systems involved
You need to know all of the sub-systems involved with the system you are working with. Just because you are working on an engine discrepancy, don’t overlook other components that can play into the system. For example, safety switches on landing gear, switches on power levers, etc. can be tied in to the system. Make sure you keep all factors in mind.
Take it one step at a time. Remember that time is money. Just as you don’t want to remove all the components at once, you also want to be focused in your troubleshooting efforts. Eliminate one component or sub-system at a time until the solution is solved. If troubleshooting charts are available, use them. These charts are arranged to get you to the solution quicker and using them assists you in your job.
Rely on experience
A good thing to keep in mind is that it can be helpful to rely on experience when tackling a discrepancy. If you have never seen a particular problem, it can be helpful to ask your co-workers for advice. Garrett’s Mark Huddleston, a lead on the TFE731 line crew, shared the value of this. A lot of times the maintenance manual will give you a good solution, but there are some instances where specific operating environments or flight operations can affect the aircraft differently. Relying on others that may have seen the same problem before can be valuable sources of information.
Spotlight
If relying on experience of others in troubleshooting can be valuable, then what about a mechanic who works in a small shop? Who can he turn to? Well, now he can turn to the Internet. Honeywell offers a program called Spotlight that helps mechanics in their troubleshooting efforts on Honeywell engines. The program is Internet-based and is available to operators and repair shops that work on Honeywell products.
The basis of Spotlight is that the program is based on feedback from the field. It relies on information entered by maintenance personnel on problems they have encountered in their troubleshooting events. Honeywell is encouraging operators and maintenance organizations to use the system to help build the database. Garrett Aviation is one company that is using the system. While visiting Garrett’s Springfield facility, Wieprecht walked me through the process of working with Spotlight.
Spotlight is quite similar to a troubleshooting chart, only electronic. When a mechanic starts a session, he enters the aircraft he is working on and the engine model. From there, he is presented with a variety of drop-down menus that narrow down the problem. Once the problem is narrowed down, a solution if offered. This can be a sequence of steps. For example, it could ask you to check a certain component on the engine. If that checks out fine, then you enter that into the computer. It will then offer the next step in the solution process. This continues until the troubled part is found and the solution is implemented.
The great thing about Spotlight is that it learns as people enter information. For example, if the problem is not solved by Spotlight, the user has a menu offered where he or she can enter the fact that a solution was not found, and enter what he or she ended up finding as a solution. This information then goes to Honeywell where it is analyzed. If it is a legitimate solution, it is then entered in the system so that it is available to all future users of Spotlight. This is a way to monitor the solutions that Spotlight recommends. Solutions are not automatically updated when someone enters new information into the system, but rather reviewed by Honeywell and then the system is updated. This is also a good tool for Honeywell to be able to update manuals as needed.
Some mechanics may be hesitant to use Spotlight because of the time necessary to enter the information. But it can be well worth the time. As more and more people use the system, troubleshooting discrepancies will become easier in the future.
