AM Aircraft Maintenance Inspection & Troubleshooting 3 — Questions and Answers
Question 1: A pitot-static system leak check is performed and the altimeter does not hold its reading. Which regulation governs the required accuracy and test interval for this system on an IFR aircraft?
- 14 CFR 91.207
- 14 CFR 91.411 and 91.413 (Correct answer)
- 14 CFR 43.15
- 14 CFR 65.81
Correct answer: 14 CFR 91.411 and 91.413
14 CFR 91.411 mandates an altimeter and pitot-static system check every 24 calendar months for IFR flight.
Question 2: During a borescope inspection of a reciprocating engine cylinder, you observe a gray, sooty deposit on the piston crown. This is MOST indicative of:
- Detonation damage
- Normal combustion byproducts from a slightly rich mixture (Correct answer)
- Water contamination in the fuel
- Excessive valve guide wear
Correct answer: Normal combustion byproducts from a slightly rich mixture
Light gray sooty deposits on a piston crown are typical of rich mixture combustion and are generally within acceptable limits.
Question 3: An aircraft's magnetic compass consistently reads 5° east of actual heading on all headings. This error is MOST likely caused by:
- Compass card calibration deviation
- Excessive compass fluid leak
- A nearby electrical component inducing a fixed deviation (Correct answer)
- Variation between magnetic and true north
Correct answer: A nearby electrical component inducing a fixed deviation
A consistent deviation in one direction on all headings typically indicates a nearby magnetic field, such as an electrical component, inducing a fixed error.
Question 4: When torquing a spark plug into an aircraft engine cylinder, the correct procedure after reaching the specified torque is to:
- Apply anti-seize compound to threads and re-torque
- Safety-wire the plug to the ignition harness lead
- Record the torque value in the engine logbook
- Verify the gap and install the lead, then verify proper firing during runup (Correct answer)
Correct answer: Verify the gap and install the lead, then verify proper firing during runup
After torquing, the ignition lead is installed and proper plug firing is confirmed during the engine runup magneto check.
Question 5: A hydraulic system pressure gauge fluctuates rapidly during gear retraction. The MOST probable cause is:
- Air trapped in the hydraulic system (Correct answer)
- A faulty pressure gauge snubber
- Hydraulic pump cavitation due to low reservoir level
- Excessive back-pressure in the return line
Correct answer: Air trapped in the hydraulic system
Rapid pressure gauge fluctuation during actuation is the classic symptom of air trapped in the hydraulic system, causing inconsistent pressure.
Question 6: Which of the following NDT methods is BEST suited for detecting a subsurface fatigue crack in an aluminum wing spar?
- Dye penetrant inspection
- Magnetic particle inspection
- Eddy current inspection (Correct answer)
- Visual inspection with 10x loupe
Correct answer: Eddy current inspection
Eddy current inspection detects subsurface defects in conductive materials like aluminum without requiring contact or disassembly.
Question 7: After replacing a primary flight control cable, the mechanic must verify:
- Cable tension using a tensiometer and correct turnbuckle safety method (Correct answer)
- Cable part number matches the airframe log only
- That no more than three broken wires exist in any one-foot section
- Cable routing using the aircraft's weight and balance data
Correct answer: Cable tension using a tensiometer and correct turnbuckle safety method
Control cable tension must be measured with a tensiometer and turnbuckles must be safetied per approved methods after any cable replacement.
AM Aircraft Maintenance Inspection & Troubleshooting 3
A pitot-static system leak check is performed and the altimeter does not hold its reading.
Which regulation governs the required accuracy and test interval for this system on an IFR aircraft?