2A654 Volume 3 CDC

When a mixed sealant will not wet the surface, it means that it is not able to spread evenly and adhere properly to the surface it is being applied to. This can be due to various reasons such as the wrong consistency or improper mixing of the sealant. In such cases, the sealant will not be effective in creating a proper seal and should be discarded.

In an ideal installation of a bolt on an aircraft component, the grip length of the bolt should be slightly shorter than the thickness of the materials being joined. This ensures that the bolt provides a secure and tight connection between the materials without protruding too far, which could cause interference or damage. Having the grip length slightly shorter also allows for proper tensioning of the bolt, ensuring that it can withstand the forces and vibrations experienced during aircraft operation.

The integral tank may be a prime location for fungus growth because of condensational buildup. Condensation occurs when warm air comes into contact with a cold surface, causing moisture to form. In an integral tank, there may be areas where moisture can accumulate, such as corners or crevices. This moisture, combined with the dark and stagnant environment of the tank, creates a favorable condition for fungus to grow.

Brass should never be used to make a sealant scraper because it is a relatively soft material compared to other options like phenolic block, aluminum, and hardwood. The purpose of a sealant scraper is to effectively remove sealant or adhesive residue from surfaces, and a soft material like brass would not be able to provide the necessary strength and durability for this task. It could easily wear down or deform, making it ineffective for scraping. Therefore, brass is not a suitable material for a sealant scraper.

The fuel cell/tank servicing cart should be positioned inside the fuel system repair area. This ensures that it is easily accessible and in close proximity to the fuel system, allowing for efficient and convenient servicing of the fuel cell/tank. Placing it inside the repair area also helps to maintain a clean and organized workspace for fuel system repairs.

A fuel tank without foam is considered "entry-safe" when the atmospheric condition inside the tank is at 10 percent LEL (Lower Explosive Limit). LEL refers to the minimum concentration of a flammable substance in the air that can ignite. A lower LEL indicates a safer environment as it means there is a lower risk of an explosion or fire. Therefore, a 10 percent LEL is considered safe for entry into a fuel tank without foam.

In monocoque aircraft fuselage construction, weight becomes a problem. Monocoque construction involves the use of a single shell or skin to bear the majority of the structural load, which means that the skin must be strong enough to support the entire weight of the aircraft. This can result in a heavier overall structure compared to other types of construction, such as truss or cantilever, where the load is distributed among multiple structural elements. Therefore, weight becomes a concern in monocoque construction.

The extent of corrosion on an aircraft surface depends on the length of time electrolytes are in contact with the metals. Electrolytes, such as water or saltwater, can accelerate the corrosion process by providing a medium for the transfer of ions between the metal and the environment. The longer the electrolytes are in contact with the metals, the more time they have to cause corrosion. Therefore, the length of time electrolytes are in contact with the metals is a crucial factor in determining the extent of corrosion on an aircraft surface.

The stringers in an integral tank provide attachment points for the skin. This means that they are responsible for connecting and securing the outer layer of the tank, ensuring that it remains in place and maintains its shape. Without the stringers, the skin would not have a solid foundation to be attached to, and the tank would not be structurally sound. Therefore, the stringers play a crucial role in providing support and stability to the tank's overall structure.

Skinning refers to the formation of a skin or crust on the surface of the liquid sealant. This can occur when the sealant is exposed to air for a prolonged period, causing it to dry and harden on the surface. Skinning makes the sealant unserviceable because it affects the consistency and usability of the product. It becomes difficult to mix and apply the sealant properly when a skin has formed, leading to compromised sealing performance. Therefore, a container of unmixed liquid base or accelerator sealant with skinning is considered unserviceable.

The minimum hose length from the ambient breathing air pump to the respirators is 50 feet. This length is necessary to ensure that there is enough distance for the air to travel and be filtered properly before reaching the respirators. A longer hose also allows for more flexibility and mobility for the users while still maintaining a safe distance from the pump. A shorter hose may not provide sufficient filtration and could potentially compromise the quality of the air being breathed in by the users.

To prepare the surface for the new fillet after removing the defective sealant, it is recommended to abrade 1/2 inch from the ends of the fillet. This ensures that the surface is properly roughened and ready to bond with the new fillet, providing a secure and effective seal. Abrading too close to the ends may compromise the strength of the fillet, while abrading too far may result in an inadequate bond. Therefore, abrading 1/2 inch from the ends strikes a balance between these factors, ensuring a reliable and durable seal.

Plastic film is used to test applied sealant for a tack-free condition. This is because when the sealant is applied, it needs to dry or cure to a certain degree before it can be touched or handled. By placing a plastic film over the sealant and gently pressing on it, one can check if the sealant has reached the desired tack-free state. If the sealant sticks to the film, it is not yet tack-free, but if it does not stick and is dry to the touch, it indicates that the sealant has cured properly.

The oylite stik is the only temporary repair method listed that has an immediate cure time. This means that once the oylite stik is applied, it will harden and cure immediately, providing an instant temporary fix. The other options listed may require some additional time for the epoxy to cure or set properly before the repair is complete.

A double cup assembly is used to locate a leak source by forcing dye solution through the leak exit point. This assembly consists of two cups that create a seal around the leak area, allowing the dye solution to be injected under pressure. The pressure forces the dye solution to flow through the leak exit point, making it easier to identify the source of the leak.

Aircraft which are adjacent to an open fuel system repair area must not be operated under their own power within 100 feet. This is because operating an aircraft under its own power in close proximity to an open fuel system repair area can pose a significant safety risk. The potential for fuel leaks or ignition sources in the repair area increases the risk of fire or explosion if the aircraft is operated within 100 feet. Therefore, it is necessary to maintain a safe distance of 100 feet to mitigate these risks and ensure the safety of personnel and equipment.

During the preparation of an aircraft for fuel systems maintenance, the AF form 979, Danger tag of AF form 1492, warning tag, must be placed on the aircraft's fuel control panel and external power receptacle. This is necessary to ensure that anyone approaching the aircraft is aware of the potential danger associated with the fuel control panel and the external power receptacle. By tagging both of these components, it helps to prevent accidental activation or interference with the fuel system and electrical power supply during maintenance operations.

After removing the access door, the next step in blow purging an aircraft fuel tank is to place the duct in the tank opening. This is necessary in order to direct the flow of air into the tank and facilitate the removal of any flammable vapors or gases. By placing the duct in the tank opening, the air can be properly circulated and the tank can be effectively purged before any maintenance or repairs are conducted.

The double cup assembly is used to locate a leak source by forcing dye solution through the leak exit point. This assembly consists of two cups that create a seal around the leak area, allowing the dye solution to be injected under pressure. The pressure forces the dye solution through the leak exit point, making it easier to identify the source of the leak.

Jo-bolts are fasteners that are specifically designed to be installed in situations where access to only one side of the work is possible. They consist of a threaded rod with a specially designed head that can be installed from one side and secured with a nut on the other side. This makes them ideal for use in integral tanks where it may be difficult or impossible to access both sides of the work.

The MC-7 Air compressor is capable of delivering high volumes of air. This means that it can produce a large amount of compressed air, making it suitable for applications that require a high flow rate. This feature makes the MC-7 Air compressor efficient and effective in tasks such as powering pneumatic tools, inflating tires, or operating machinery that relies on compressed air.

Applying a maximum of 100 psi air pressure to the sealant is an acceptable method of checking its adhesion. This method tests the integrity of the sealant by subjecting it to a controlled amount of pressure. If the sealant remains intact and does not show any signs of separation or detachment, it indicates good adhesion to the surface. This method is commonly used in aerospace and other industries to ensure the quality and effectiveness of sealant applications.

A plug is a basic type of access door that opens into the fuel tank, providing a tighter seal than other types. The term "plug" refers to a solid object that can be inserted or removed to open or close an opening. In this case, the plug acts as a door that can be opened to access the fuel tank and closed to create a tight seal, preventing any leakage or contamination. This type of access door is commonly used in fuel tanks to ensure the safety and integrity of the fuel system.

The size and cut of the nozzle determine the size of the applied fillet on the filleting gun. The nozzle controls the flow of material, and its size and shape directly affect the amount and shape of the fillet being applied. A larger or differently shaped nozzle will result in a different size or shape of the fillet, while a smaller or differently cut nozzle will produce a smaller or differently cut fillet. Therefore, the size and cut of the nozzle are crucial factors in determining the size of the applied fillet.

The correct answer is a yellow "REMOVE BEFORE FUELING/DEFUELING" streamer attached. This is because during the fueling or defueling process of an aircraft, it is crucial to ensure that all vent plugs are removed to prevent any blockages or restrictions in the venting system. The yellow streamer serves as a visual reminder to the ground crew that the vent plug needs to be removed before the fueling or defueling process begins.

The masonry fire restrictive construction of a new facility must meet a minimum standard of 1 hour. This means that the construction should be able to resist the spread of fire for at least 1 hour, providing a certain level of fire protection and safety for the occupants of the facility. This standard ensures that the masonry construction is able to withstand the heat and flames of a fire for a reasonable amount of time, allowing for evacuation and firefighting efforts to take place.

Lockwashers should be installed with screws and bolts whenever the self-locking or castellated nut is not used. Lockwashers are designed to prevent loosening or rotation of the fastener by creating tension between the nut and the bolted surface. They provide a secure and reliable connection, reducing the risk of loosening due to vibrations or other external forces. By using lockwashers, the fasteners can maintain their tightness and keep the hardware in place, ensuring the stability and safety of the installation.

Aluminum alloy tubing is the most widely used because it can be easily flared with hand tools. This means that it can be easily shaped and manipulated to fit various applications and requirements.

The given description indicates that there is some damage to the protective coating and the metal is discolored, but the pitting is only one mil deep. This suggests that the corrosion is not very extensive and is considered to be light.

The correct answer is "before the end of sealant application life" because applying final torque to a wet installed fastener before the sealant application life ends ensures that the fastener is properly tightened and secured while the sealant is still in its optimal state. If the torque is applied after the sealant application life ends, there is a risk that the sealant may have already cured or hardened, which could affect the effectiveness of the fastener installation.

During the delivery preparation phase of depot maintenance, a temporary repair should not exceed one per tank. This means that only one temporary repair should be made for each tank being worked on. Making more than one repair per tank during this phase may lead to complications or errors in the maintenance process.

A pin punch is used to drive out pins that are too deep for a starting or drift punch. A pin punch has a long, slender design with a pointed tip that allows it to reach into tight spaces and apply force to the pin. It is specifically designed for removing pins and can effectively drive them out without causing damage to the surrounding material.

The T477W bonging meter displays values in milliohms. This means that the meter measures electrical resistance in units of milliohms, which are equal to one thousandth of an ohm.

An installed exhaust fan is used in a fuel system repair facility to extract fuel vapors outside the facility during operations like defueling and air purging. This equipment helps to maintain a safe and clean working environment by removing potentially hazardous fumes and preventing their accumulation within the facility. It ensures proper ventilation and reduces the risk of fire or explosion caused by the buildup of fuel vapors.

Truss construction is a type of fuselage construction that uses a fabric or thin metal covering and is commonly found on small, lightweight aircraft. In truss construction, the load-bearing structure consists of a series of interconnected triangular frames, which provide strength and support to the aircraft. This type of construction is lightweight, cost-effective, and relatively easy to repair, making it suitable for smaller aircraft where weight and simplicity are important factors.

When a fuel tank is siphon inerted, it means that the oxygen has been removed from the tank to prevent combustion. Therefore, the proper reading on an oxygen analyzer for such a tank would be low or close to zero percent. Among the given options, the closest value to zero percent is 9 percent, making it the correct answer.

Ribs are structural components that form the end boundaries of an integral tank. Ribs are long, narrow, and curved structures that provide strength and support to the tank. They are typically placed perpendicular to the longitudinal axis of the tank and are attached to the skin of the tank. Ribs help to distribute the load evenly across the tank and prevent deformation or collapse. They also add rigidity and stability to the tank structure, ensuring its integrity and durability.

The most preferred temporary repair method is the hardman epoxy with aluminum foil patch. This method is preferred because the hardman epoxy provides a strong and durable bond, while the aluminum foil patch adds an extra layer of protection and reinforcement. Together, they create a reliable temporary repair solution that can withstand various conditions and provide a long-lasting fix.

A safety guard must be stationed at the fuel cell/tank servicing cart each time the air supply system is used. This is important because the air supply system is a critical component of the cart and its operation can pose potential risks or hazards. Having a safety guard present ensures that proper safety measures are followed and any issues or emergencies can be addressed promptly.

A field permit can be issued for a maximum period of one year. This means that the permit allows the holder to use the field for various activities, such as events, sports, or farming, for a duration of up to one year. This longer time frame provides flexibility and convenience for the permit holder to plan and carry out their activities on the field without the need for frequent renewals or extensions.

When using an MA-1 blower to exhaust purge a fuel tank, the filter must be removed. This is because the purpose of exhaust purging is to remove any contaminants or impurities from the fuel tank, and the filter could potentially trap these contaminants and prevent them from being effectively removed. By removing the filter, the blower can more efficiently exhaust purge the fuel tank and ensure that it is thoroughly cleaned.

The correct answer is after every day of use. This means that the pneumatic blower unit should have 1/2 oz. of oil added to it at the end of each day that it is used. Adding oil after every day of use helps to ensure that the blower unit remains properly lubricated and functioning efficiently.

The Maintenance Group Commander is responsible for signing the Master Entry Permit and ensuring that all safety and health requirements are met. This includes overseeing the maintenance operations and ensuring that proper safety protocols are followed to prevent any accidents or hazards. They have the authority and knowledge to ensure that all necessary precautions are taken before any work is carried out, making them the appropriate person to sign the permit.

The correct answer is MIL-H-27267. This type of hose is a medium pressure Teflon hose with an operating temperature range of 65 to 450* F.

In a maintenance preparation checklist, ensuring that all support equipment used in a fuel system is bonded is important. Bonding refers to the process of connecting all metal parts of the equipment to prevent the buildup of static electricity. This is crucial in fuel systems to prevent the occurrence of sparks that could potentially ignite fuel vapors, leading to a fire or explosion. By bonding the support equipment, the risk of static electricity discharge is minimized, ensuring the safety of the fuel system and preventing any potential accidents.

When attempting to locate a leak exit point on or near a common tank boundary, the first step should be to defuel the outboard tank. This is because the outboard tank is located on the outer side of the common tank boundary and is more likely to have a leak that can be detected. By defueling the outboard tank, it reduces the amount of fuel that needs to be inspected and allows for a more focused search for the leak exit point.

MIL-S-83430 is the correct answer because it is a high-adhesion sealant that is specifically designed for limited service life at temperatures up to 360 F. The other options, MIL-S-8802, MIL-S-81733, and MIL-S-83318, may be high-adhesion sealants but they are not designed for use at temperatures up to 360 F.

Rescue team training documentation is not a required element of the written emergency response plan. While it is important for the rescue team to undergo training, documenting this training is not necessary for the emergency response plan itself. The plan should include practice rescue, roles of emergency agencies, and rescue from IDLH (Immediately Dangerous to Life or Health) environments as these are crucial elements in responding effectively to emergencies.

The first step in performing the talcum powder method of leak detection is to strip the exterior seals. This involves removing any seals or gaskets that cover the potential areas of leakage. By doing this, the technician can expose the surfaces where the talcum powder will be applied. This step is crucial as it ensures that the powder can directly come in contact with the surfaces and effectively detect any leaks that may be present.

Vacuum dye should only be used after all other methods have failed to isolate the leak source because it is a more invasive and time-consuming method. Vacuum dye involves creating a vacuum within the system and introducing a dye that will be drawn into the leak, making it visible under UV light. This method is typically used as a last resort when other methods, such as pressure testing or dye injection, have been unsuccessful in locating the source of the leak.

To prevent the formation of air bubbles, the first fillet seal should be thoroughly worked into the structure. This can be done effectively using a sealant spatula, which allows for precise application and ensures that the sealant is evenly distributed. Working the sealant into the structure helps to eliminate any trapped air, ensuring a secure and reliable seal. Using a sealant injection gun or a filleting gun filled with class A sealant may not provide the same level of control and precision, increasing the risk of air bubbles forming.

The pressure ratio for the high-pressure injection gun is 70 to 1. This means that the pressure of the gun is 70 times higher than the initial pressure. This high pressure allows for efficient and effective injection of substances into the desired target.

A sealant filleting gun is used for low-pressure injection seals. This type of gun is specifically designed for applying sealant in a precise and controlled manner along the edges or fillets of a joint. It allows for accurate placement of the sealant, ensuring a proper seal without any excess or wastage. This method is commonly used in various industries such as construction, automotive, and aerospace, where a reliable and efficient seal is required.

A plenum chamber must be used with the MC-1 heater to reduce the temperature of the air coming from the heater. A plenum chamber is a device that helps distribute and mix the heated air evenly throughout a space. It allows for the air to cool down before being released into the area, ensuring that the temperature is suitable for the intended application.

The MC-1A support equipment item has both low- and high-air pressure systems.

JP-5 is the only acceptable item for use in fluid purging an aircraft fuel tank. The other options mentioned, JP-4, MIL-C_38736, and P-D-680, Type II, are not suitable for this purpose.

A ventilation trailer is an equipment item that provides rapid purging of fuel tanks and supplies breathing air. It is specifically designed to ventilate and remove fumes from confined spaces such as fuel tanks. It ensures the safety of workers by providing a continuous supply of clean breathing air while purging the tanks. The other options, such as an air/nitrogen servicing trailer, fuel cell/tank servicing cart, and ambient breathing air pump, do not specifically mention the capability of rapid purging of fuel tanks and supplying breathing air, making them incorrect choices. Therefore, the correct answer is the ventilation trailer.

If a leak develops between faying surfaces of an aircraft structure that was sealed with structural adhesive, the best way to repair it would be to apply a curing-type fillet or overcoat. This involves applying a layer of the same type of adhesive used initially to seal the surfaces. This method ensures that the leak is effectively sealed and the structural integrity of the aircraft is maintained.

The proper reading on an oxygen analyzer for a fuel tank that has been pressure inerted is 4 percent. This means that the oxygen level inside the fuel tank is at 4 percent, indicating that the tank has been properly inerted to prevent the risk of fire or explosion.

The entry authority should forward the canceled entry permit to the Ground Safety Office. This is likely because the Ground Safety Office is responsible for handling and managing safety-related matters, and the canceled entry permit may contain important information or records that need to be kept for safety purposes.