ACS Study Guide 2026
Everything you need to pass the ACS exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 ACS Exam Format at a Glance
📚 ACS Topics to Study (69)
✍️ Sample ACS Questions & Answers
1. An aircraft's altimeter was found to be inaccurate during a transponder/altimeter inspection. Under 14 CFR 91.411, the aircraft may be flown in controlled airspace under IFR:
14 CFR 91.411 prohibits flight in controlled airspace under IFR with an altimeter system that does not meet accuracy requirements; it must be repaired and retested.
2. During engine assembly, what is the correct procedure for installing a new oil seal on a crankshaft?
Oil seals should be lubricated on the sealing lip with clean engine oil to prevent lip damage during installation and initial start-up, and pressed squarely to the correct depth.
3. Which NDT method is most appropriate for detecting internal voids and delaminations in composite aircraft structures?
Ultrasonic testing and tap testing are the primary methods for detecting internal defects such as voids and delaminations in composite structures.
4. A suspected unapproved part (SUP) is discovered during maintenance. The correct action is to:
FAA Order 8120.10 directs mechanics to remove SUPs from service, quarantine them, and report to the FAA's Suspected Unapproved Parts Program.
5. Which type of brake system uses a single-disc design with one puck-style actuating cylinder on each side?
A single-disc floating caliper brake uses one rotor disc and a caliper that floats to apply equal pressure from both sides with pistons.
6. An aircraft engine fails to develop full static RPM during a pre-takeoff run-up. The magneto check is normal. What should be checked next?
A constant-speed propeller set to too coarse a pitch or a malfunctioning governor will prevent the engine from reaching full static RPM despite normal ignition.