ACS Troubleshooting Techniques & Inspection Standards 2 — Questions and Answers
Question 1: When troubleshooting an aircraft hydraulic system that loses pressure only during high-demand operations, what is the most likely cause?
- Worn hydraulic pump with insufficient flow capacity (Correct answer)
- Contaminated hydraulic fluid
- Incorrect hydraulic fluid viscosity
- A leaking brake line
Correct answer: Worn hydraulic pump with insufficient flow capacity
A worn pump may maintain static pressure but fail to deliver sufficient flow under high demand, causing pressure drop during multiple simultaneous actuations.
Question 2: During an annual inspection, you find a crack in an aircraft's aluminum skin near a rivet hole. What is the correct procedure?
- Report it in the maintenance log and defer repair
- Measure the crack, determine if it exceeds limits, and consult manufacturer's structural repair manual (Correct answer)
- Immediately ground the aircraft and replace the entire panel
- Apply a patch and return to service without documentation
Correct answer: Measure the crack, determine if it exceeds limits, and consult manufacturer's structural repair manual
The mechanic must measure the defect, compare it against the manufacturer's allowable limits in the SRM, and follow approved repair procedures.
Question 3: An aircraft engine exhibits black smoke from the exhaust. This symptom most likely indicates:
- Lean fuel-air mixture
- Rich fuel-air mixture or excessive fuel flow (Correct answer)
- Oil burning due to worn piston rings
- Ignition timing advanced too far
Correct answer: Rich fuel-air mixture or excessive fuel flow
Black exhaust smoke is a classic indicator of a rich mixture or excessive fuel flow resulting in incomplete combustion.
Question 4: What does a 'red arc' on an aircraft instrument face represent?
- Normal operating range
- Caution or precautionary range
- Never-exceed or maximum limit (Correct answer)
- Manufacturer-recommended cruise range
Correct answer: Never-exceed or maximum limit
A red arc or red radial line on an instrument denotes a never-exceed speed or maximum operating limit that must not be exceeded.
Question 5: When performing a 100-hour inspection on a reciprocating engine, a mechanic finds the oil consumption has doubled since the last inspection. The most likely cause is:
- Using the wrong grade of oil
- Worn or stuck piston rings (Correct answer)
- A clogged oil filter
- Incorrect oil pressure setting
Correct answer: Worn or stuck piston rings
Worn or stuck piston rings allow oil to enter the combustion chamber and be burned, significantly increasing oil consumption.
Question 6: A pitot-static system check reveals the altimeter reads 200 feet higher than field elevation with the static port open on a standard day. This indicates:
- The altimeter is functioning correctly within tolerance
- A leak in the static system that must be repaired
- The altimeter has an excessive scale error requiring calibration or replacement (Correct answer)
- The aircraft is at a higher elevation than the airport reference point
Correct answer: The altimeter has an excessive scale error requiring calibration or replacement
An altimeter error of 200 feet at field elevation exceeds the FAA allowable tolerance of ±75 feet and requires calibration or replacement.
Question 7: During a borescope inspection of a turbine engine combustion section, you observe hot spots and discoloration on the combustion liner. The next step should be:
- Continue operating with increased monitoring intervals
- Compare findings to engine manufacturer's limits and serviceable criteria (Correct answer)
- Immediately replace the combustion liner without further analysis
- Apply a protective coating to the discolored area
Correct answer: Compare findings to engine manufacturer's limits and serviceable criteria
Borescope findings must be compared against the manufacturer's inspection criteria to determine if the component is serviceable, requires repair, or replacement.
ACS Troubleshooting Techniques & Inspection Standards 2
When troubleshooting an aircraft hydraulic system that loses pressure only during high-demand operations, what is the most likely cause?