Engineering Homework Help

Read each thread and reply each thread with your thought. (write two reply, 250 words each)

Thread 1

During an annual inspection of a Piper Cherokee PA-28-180 earlier this year I was asked to troubleshoot a circuit on the customer’s aircraft in which the pitot heat circuit was overloading and tripping the pitot heat circuit breaker consistently after resetting each time. The aircraft was a 14-volt direct current electrical system. I know that the pitot heat is one of the higher amperage circuit breakers because the heating element requires higher-than-average power than a typical circuit on an aircraft. I first used continuity on my multimeter, which told me that I did indeed have continuity from the circuit breaker to the pitot heat, and from the pitot heat to the ground. Something else was wrong.

It was at this point I could have used the RED model of critical thinking. In this model the first step is to Recognize Assumptions, the second step is to Evaluate Arguments, and the third step is to Draw Conclusions (Centre for Executive Education, 2017). The first step has you question the information presented and/or see it from a different perspective. I could have questioned the information presented, and I’ll get to that in a minute, or I could have asked someone else what they thought. The second step is another questioning of the information for its quality and by staying objective, without emotions fogging the process. Question this information presented to me would have been useful because it might have told me that continuity works with resistors that are >30 ohms when I’m really looking for close to 0 ohms of resistance from the circuit breaker to the pitot tube heating element.

Through a lot of unnecessary wire cutting and I was able to isolate the problem to specific connectors, knife disconnect splices, in the circuit in which they had corroded due to dissimilar metal corrosion. Instead of just going through the motion I should have stopped and thought about things. “The critical thinker, though, stops to consider whether or not those thoughts really make sense” (Greig, 2017). I know why I acted this way though, and it was a combination of emotions and impairment. It was the end of the day so I’m sure I was frustrated, but mostly I was exhausted from the heat and tired from working all day leading me to poor decisions. I did call it a day after that and came in with fresh eyes and a new attitude the next morning and I replaced the 50+ year old connectors with new knife disconnect splice connectors and anti-chafe sleeves over them and the system tested good.

Personally, I can improve my critical thinking skills by stopping and thinking about the whole enchilada and making decisions that make logical sense instead of just “going along” like Greig mentions in his article. Alternatively, the RED model would have helped me be efficient by questioning my own actions to begin with before I got so deep in more problems.

Thread 2 

LHR Recovery Mission

     Dr Richard Paul best analogized the R.E.D. model of critical thinking when he descriptively said that critical thinking is “thinking about your thinking while you’re thinking in order to make your thinking better.” (Greig, 2017, Pg. 28) Based on his statement, one could think they are possibly overthinking something. Applying this model to aviation maintenance and troubleshooting gives a good model for an AMT to step back, take a deep breath, and analyze the problem at hand. I’m going to share an experience I had several years ago that fits this model.

     Quite a few years ago I was a maintenance supervisor with Continental Airlines, and my team and I were tasked with recovering a B757 type aircraft in London, Heathrow (LHR) that had experienced engine pressure ratio (EPR) issues on the number one engine. The powerplant for this fleet type was a Rolls Royce, RB-211 engine. My team of technicians included two engine shop mechanics and one other technician who was qualified along with myself to run the engines. The team performed troubleshooting steps and determined the fuel flow governor, (FFG) was at fault and was subsequently replaced.

     While performing initial operation checks required by the maintenance manual for replacement of the FFG, we discovered that the engine bleed pressure light for the same engine remained on, and we had 30 psi of pressure despite the switch being in the off position.  One of the operational checks calls for the engine bleeds to be off and zero pressure. At this time, we couldn’t continue and had to stop to troubleshoot this newly found issue. This issue is a great example of the R.E.D. model which was applied to fix the airplane.

     The challenges the team overcame were through use of the R.E.D. model of recognizing assumptions, evaluating arguments, and drawing conclusions. (Chartrand, Et al, 2009)

    The assumption by my team was that because there were no previous discrepancies on the engine bleed system, the issue must have been caused by something they did when they replaced the FFG, which also lead to initially evaluating arguments between the three techs I was with. In his book, Mostia made the statement that learning comes from information and skills, (Mostia, 2006) and this was certainly applicable to this situation.

     I had 3 different technicians with different backgrounds who each had a varied opinion on what could be the issue with the engine bleed.

     I was not only a supervisor at the time, but also was a maintenance taxi and engine run instructor and was familiar with the two separate systems on the engine. The FFG originally replaced is part of the engine control relating to fuel delivery to the engine, and the engine bleed is used to extract air from the engine. Technically speaking, experience was used to draw the conclusion that one problem was not related to the other.

    Once I got the team all on the same page, we troubleshot the engine bleed issue to a pressure regulating and shut-off valve, (PRSOV) replaced the part when received the next morning and performed operational checks for both systems and returned the aircraft back into service.

    In conclusion, this is a good example of thinking through the problem rather than reacting to the problem that could have resulted in an erroneous decision. Contextually, the R.E.D model of critical thinking certainly applied to this example.