ACS Airframe Systems & Structural Maintenance 2 — Questions and Answers
Question 1: When inspecting a riveted skin joint, you find a rivet with a shop head that is too small. What is the correct corrective action?
- Drill out and replace the rivet with the next larger diameter
- Apply epoxy adhesive to fill the gap around the rivet
- Leave in place if the shop head diameter is at least 1.2 times the rivet diameter
- Drill out and replace with the same diameter rivet driven correctly (Correct answer)
Correct answer: Drill out and replace with the same diameter rivet driven correctly
An undersized shop head indicates improper driving; the rivet must be drilled out and replaced using correct driving technique with the same specification rivet.
Question 2: Which type of structural damage is classified as 'negligible' and requires no repair according to the aircraft SRM?
- A crack that has been stop-drilled
- Minor scratches or nicks that do not exceed allowable depth limits (Correct answer)
- Dents with sharp radii at the bottom
- Any corrosion visible to the naked eye
Correct answer: Minor scratches or nicks that do not exceed allowable depth limits
Negligible damage is surface damage within manufacturer-specified allowable limits that does not affect structural integrity and requires no repair.
Question 3: What is the primary purpose of a drain hole in an aircraft control surface?
- To reduce the weight of the surface
- To prevent moisture accumulation that can cause corrosion and balance issues (Correct answer)
- To allow pressure equalization during altitude changes
- To provide access for internal inspection without disassembly
Correct answer: To prevent moisture accumulation that can cause corrosion and balance issues
Drain holes prevent moisture buildup inside control surfaces, which can cause corrosion and shift the balance of the surface, affecting flight characteristics.
Question 4: When performing a repair to aircraft fabric covering using the brush method, the fabric patches should overlap the damaged area by a minimum of:
- 1/2 inch on all sides
- 1 inch on all sides
- 2 inches on all sides (Correct answer)
- 3 inches on all sides
Correct answer: 2 inches on all sides
FAA AC 43.13-1B specifies that fabric patches must overlap the undamaged fabric by at least 2 inches on all sides to ensure adequate adhesion and strength.
Question 5: A fuselage frame made of 4130 steel tubing has a crack in a non-primary member. Which welding rod is most appropriate for repair?
- E6013
- ER70S-2 (Correct answer)
- E308L
- ER4043
Correct answer: ER70S-2
ER70S-2 is the correct TIG welding rod for 4130 chromoly steel airframe tubing repairs, providing compatible strength and weld characteristics.
Question 6: What condition is indicated when aircraft skin shows 'oil canning' between stringers?
- The skin is too thick for the structural loads
- The skin has buckled due to compression stress exceeding its stability limit (Correct answer)
- Excessive tension is stretching the skin beyond its elastic limit
- Normal behavior that requires no attention during inspection
Correct answer: The skin has buckled due to compression stress exceeding its stability limit
Oil canning is a visible buckling of thin metal skin between stringers caused by compression loads exceeding the skin's local buckling stability, and it must be evaluated per the SRM.
Question 7: During a landing gear retraction test, the gear takes longer than the published time to retract. What is the FIRST area to check?
- Actuator cylinder for internal leakage
- Hydraulic system fluid level and accumulator pressure (Correct answer)
- Gear door rigging and interference
- Uplock hook spring tension
Correct answer: Hydraulic system fluid level and accumulator pressure
Low hydraulic fluid level or insufficient accumulator pressure is the most common and easily checked cause of slow gear retraction before investigating actuators or rigging.
ACS Airframe Systems & Structural Maintenance 2
When inspecting a riveted skin joint, you find a rivet with a shop head that is too small.
What is the correct corrective action?