AFS7

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Questions and Answers

What is the characteristic of a stain in terms of wet area in a 30-minute period?

More than ¾ of an inch in diameter

Up to 1.5 inches in diameter

Up to 4 inches in diameter

Less than ¾ of an inch in diameter (correct)

What is the primary source of fuel leaks in integral tanks?

Cracked fuel tank walls

Loose fasteners such as rivets, screws or bolts (correct)

Worn-out tank sealant

Loose structural members

What should be done to maximise the likelihood of a leak showing up during inspection?

Refuel the tank to maximum capacity with the recommended fuel (correct)

Inspect the tank in a well-ventilated area

Refuel the tank to half capacity

Use a specialized leak detection tool

What is the characteristic of a heavy seep fuel leak?

It will not flow or drip from the surface it clings to Signup and view all the answers

Why is it recommended to inspect tanks for other leaks and complete repairs with one tank entry?

To reduce the risk of missing other leaks Signup and view all the answers

What should be used to wipe over wet areas after detecting a fuel leak?

A lint-free cloth Signup and view all the answers

Where is the most common place to detect running or dripping fuel?

At the lowest point of the wing or nearby fuselage Signup and view all the answers

What is the characteristic of a running leak in terms of flow and dripping?

It will readily cover a large area and will flow and drip from surfaces Signup and view all the answers

What is the purpose of using Semco 419 in fuel leak detection?

To highlight the presence of fuel leaks Signup and view all the answers

How is the fuel tank purged of explosive fumes before welding?

By passing steam through the tank Signup and view all the answers

What is the recommended method to add fuel dye to the fuel?

Add 1.6 ounces of dye to 100 gallons of fuel Signup and view all the answers

Why must fuel dyes not be added to the fuel in certain aircraft?

Because it is not permitted by the maintenance manual Signup and view all the answers

What is the pressure used to test a weld-repaired fuel tank?

Approximately 3 PSI air pressure Signup and view all the answers

What is the purpose of dusting the area with Semco 419?

To highlight the presence of fuel Signup and view all the answers

Why must the fuel tank be drained when the point of exit is determined?

To remove the leaking fuel from the tank Signup and view all the answers

What is the minimum time required for purging explosive fumes from the tank by steaming?

1 hour Signup and view all the answers

What is the primary purpose of maintenance inspections in aviation?

To reduce the likelihood of errors affecting airworthiness Signup and view all the answers

What is permitted on actuator piston rods and rotating shafts?

A thin film of oil Signup and view all the answers

What is the consequence of internal leakage beyond allowable limits?

It must be rectified according to the relevant publication Signup and view all the answers

What is an example of a method for isolating internal leakage?

Pressurising a component and then removing the opposite port line Signup and view all the answers

What is included in the term 'inspection'?

An activity conducted during or at completion of a task Signup and view all the answers

What is the purpose of inspecting fuel systems and components?

To reduce the likelihood of errors affecting airworthiness Signup and view all the answers

What is a characteristic of a successfully completed inspection?

The work has been performed satisfactorily Signup and view all the answers

What is the primary focus of hydraulic system maintenance?

To identify and rectify internal leakage Signup and view all the answers

What is the primary reason for mounting large tanks in a frame?

To prevent distortion caused by air pressure Signup and view all the answers

What is the recommended method for checking for leaks in a fuel tank?

Searching for leaks with an approved solution Signup and view all the answers

What is the primary cause of a bladder tank needing to be replaced?

Expiration of its finite life Signup and view all the answers

What is the purpose of applying anti-chafing tape in the tank bay?

To protect metal parts from chafing Signup and view all the answers

Why is it necessary to wipe the inside surfaces of a bladder tank with an approved inhibitor?

To protect the material from becoming brittle and cracking Signup and view all the answers

In what order are the fittings and covers installed on a bladder tank?

Outlet fitting and sump drain, then remaining fittings and covers Signup and view all the answers

What is the primary cause of abrasive wear on tooth surfaces?

Carried particles in the lubricant that abrade the surface Signup and view all the answers

What is the characteristic of pitting on gear surfaces?

Localised formation of rounded cavities Signup and view all the answers

What is the primary cause of cracking in gears?

Faulty heat treatment of gears Signup and view all the answers

What is the characteristic of breakage in gears?

Chunks of metal flaking away due to various faults Signup and view all the answers

What is the primary cause of interference wear on gear teeth?

Misalignment of gears or mating of teeth Signup and view all the answers

Where is the damage typically located in interference wear?

Roots and tips of gear teeth Signup and view all the answers

What is the purpose of inspecting and testing springs according to the Maintenance Manual?

To ensure proper functioning of the major assembly Signup and view all the answers

What is the significance of dark edges in gear breakage?

Indicates fatigue starting from a surface crack Signup and view all the answers

Study Notes

Inspection

An inspection is a visual or physical verification that a task/component conforms to a prescribed standard.
Inspections reduce the likelihood of errors that could affect airworthiness.
Inspections include activities conducted during or after a task to review the work carried out by a tradesperson.

Hydraulic System Maintenance

Leakage from any stationary connection is not permitted and must be rectified.
A small amount of fluid seepage may be permitted on actuator piston rods and rotating shafts.
Internal leakage beyond allowable limits must be rectified according to the relevant publication.

Leak Classification

A stain does not wet an area around the leak source of more than ¾ of an inch in diameter within a 30-minute period.
A seep won’t wet an area of more than 1.5 inches in diameter within a 30-minute period.
A heavy seep fuel leak soon reappears after being wiped away and will spread over an area of up to 4 inches within 30 minutes of being wiped.
A running leak quickly reappears after being wiped away and quickly spreads onto surrounding surfaces.

Locating External Point of Leak

Loose fasteners such as rivets, screws, or bolts are the most common source of fuel leaks in integral tanks.
Fuel can channel between attaching structural members and tank sealant.
Start examinations from the point where the leak appears externally, usually at the lowest point of the wing or nearby fuselage.

Fuel Leak Disclosing Agents

Fuel leak disclosing agents such as Semco 419 can be used to highlight the presence of fuel.
Dust the area with Semco 419 immediately after drying the surface.
Continue dusting while working toward the external point of fuel leak.

Welded Fuel Tanks

Leaks in welded tanks can be caused by cracking or damage.
These tanks must be drained and removed from the aircraft, and the leak repaired by welding.
The tank must be thoroughly purged of all explosive fumes by steaming before welding.

Bladder Tanks

Damaged bladder tanks are removed from the aircraft and repaired using an approved repair kit.
All bladder tanks have a finite life and will eventually develop leaks.
A leaking bladder tank is removed from the aircraft and replaced with a new or reconditioned tank.

Abrasive Wear and Other Gear Damages

Abrasive wear includes scratching and scoring, dependent on the size of particles carried in the lubricant.
Scoring is the heavy gouging of metal from the tooth surface as the temperature rises and the lubricant thins out.
Pitting and spalling are associated with thin oil films and high temperatures.
Cracking and breakage can be caused by faulty heat treatment or improper machining during manufacture.

Spring Inspection, Testing, and Adjusting

Inspection and testing of springs are carried out according to the Maintenance Manual applicable to the major assembly the spring is part of.

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Description

Quiz on inspection procedures in aviation maintenance, including visual and physical verification, error reduction, and hydraulic system maintenance.