FAA Aviation Mechanic Powerplant (AMP)Engine InspectionHard
A mechanic is inspecting a welded steel-tube engine mount for cracks and corrosion during an annual inspection. Which of the following findings would require the mount to be removed and repaired or replaced before further flight?
- ALight surface oxidation that wipes off with a cloth
- BSlight discoloration from engine exhaust heat
- CMinor scuffing of the paint from normal handling
- DA crack detected by dye penetrant near a welded tube junction
Show answer & explanationAnswer & explanation
Correct answer: D. A crack detected by dye penetrant near a welded tube junction
A crack near a welded joint on a structural engine mount is a serious structural defect that compromises the mount's ability to support engine loads and vibration; it requires removal and repair (typically by a certified welder) or replacement before further flight.
Why the other options are wrong
- A. Light surface oxidation is a cosmetic issue and does not affect structural integrity.
- B. Heat discoloration alone does not confirm structural weakening unless accompanied by other damage.
- C. Paint scuffing is cosmetic damage with no structural significance.
Engine Mount Inspection
Welded steel-tube engine mounts must be inspected for cracks, corrosion, and distortion, since they support engine weight and absorb vibration loads; cracks at weld joints are airworthiness-critical defects.
- Dye penetrant inspection commonly used to detect cracks near welds
- Elongated bolt holes indicate wear and require attention
- Corrosion under vibration isolators/mounts is a common problem area
- Cracked or bent mounts require repair by certified welder or replacement
Memory trick: 'Cracks at the Weld, Ground the World' — a weld crack grounds the aircraft until fixed.