Airframe Systems & Structural Maintenance Flashcards

A retractable landing gear strut that extends but will not lock down may be caused by:

Answer: A worn or misadjusted downlock mechanism, foreign object obstruction, or actuator rigging error

Failure to achieve downlock can result from a worn, broken, or misadjusted downlock hook, an obstruction in the gear bay, or an actuator that does not travel far enough to cam the lock over center.

When applying aircraft dope to a fabric-covered surface, runs or sags in the finish are caused by:

Answer: Using dope that is too thin or applying too heavy a coat in one pass

Runs and sags in aircraft dope are caused by an over-thinned mixture or applying an excessively thick coat, both of which allow the material to flow before it can flash off.

Which statement about dissimilar metal corrosion is correct?

Answer: It occurs only when metals are in direct contact in the presence of an electrolyte

Galvanic (dissimilar metal) corrosion requires both direct metallic contact between dissimilar metals and the presence of an electrolyte to complete the circuit for current flow.

When a hydraulic actuator used for flap extension shows internal bypass (fluid bypassing the piston), the symptom will be:

Answer: Flaps creep or drift from the selected position under aerodynamic load

Internal bypass allows fluid to leak past the piston seals, so aerodynamic loads on the flap can slowly move it from the selected position (creep/drift) without commanding movement.

The 'fail-safe' design concept in aircraft structures means:

Answer: Alternate load paths exist so that failure of one member does not cause catastrophic failure of the entire structure

Fail-safe design provides redundant or alternate load paths so that a single structural failure (crack, fracture) is arrested or redistributed without causing sudden catastrophic collapse.

Before applying a chemical film treatment (Alodine/Iridite) to an aluminum repair part, the surface must be:

Answer: Thoroughly cleaned and deoxidized to bare, active metal

Chemical film treatments react with bare aluminum oxide; the surface must be completely clean and freshly deoxidized so the conversion coating bonds directly with the base metal.

An aircraft's nose gear shimmy damper is found to be completely non-functional. What is the most likely consequence if the aircraft is taxied without repair?

Answer: Rapid oscillation of the nose gear that can cause structural damage to the gear and airframe

A non-functional shimmy damper allows the nose gear to oscillate rapidly (shimmy) during taxi and roll-out, generating cyclic loads that can crack the gear structure and airframe attach points.