Storage Systems - Fuel Systems - Airframes & Aircraft Systems #65

Summary

This lesson explores the different fuel storage methods in aircraft, including integral, rigid, and flexible tanks. Integral tanks are part of the aircraft's structure, offering minimal added weight and are common in large passenger planes. Rigid tanks are separate metal containers found in smaller aircraft and can be externally mounted. Flexible tanks, or fuel bladders, are used in high-performance light aircraft and military planes for their self-sealing properties. All tanks incorporate baffles to reduce fuel movement during maneuvers, and some feature baffle check valves to control fuel flow. Additional components like vents, gauging systems, and filler caps are also discussed.

Takeaways

• 🛩️ Aircraft fuel is stored in tanks that can be integral, rigid, or flexible.
• 💧 Integral tanks are formed by sealing parts of the aircraft structure like wings and stabilizers during manufacturing.
• 🔩 Rigid tanks are separate, removable containers that do not contribute to the aircraft's structural integrity.
• 🔖 Flexible tanks, or fuel bladders, are reinforced rubberized bags that are secured within the aircraft structure.
• ✈️ Modern large passenger aircraft typically use integral tanks due to their structural efficiency.
• 🏞️ Smaller general aviation aircraft often use rigid tanks, which may be mounted externally on the wingtips.
• 🔒 Flexible tanks are popular in high-performance light aircraft and military aircraft for their self-sealing capabilities.
• 🚫 Integral tanks minimize extra weight as they utilize existing aircraft structure.
• 🔄 Baffles are installed in fuel tanks to restrict fuel movement and reduce inertial forces during maneuvers.
• 💧 Baffle check valves may be used to allow fuel flow inboard but restrict outboard flow towards wingtips.

Q & A

What are the different methods for storing fuel onboard an airplane?

There are three main methods for storing fuel onboard an airplane: integral tanks, rigid tanks, and flexible tanks.

How are integral tanks created and what is their advantage?

Integral tanks are created by sealing the insides of the wings, horizontal stabilizers, and the center section torsion box during manufacture. Their advantage is that they add little extra weight to the aircraft as they are formed from the structure already required.

In which types of aircraft are integral tanks commonly found?

Integral tanks are commonly found in all modern large passenger aircraft.

What are rigid tanks and where are they typically installed?

Rigid tanks are sealed containers mounted in or on the aircraft wing or fuselage. They are typically installed in a compartment designed to accommodate the tank and are commonly found in smaller general aviation aircraft.

What material are rigid tanks usually made of?

Rigid tanks are usually made of metal and may be removed for inspection, replacement, or repair.

What is a flexible tank and what are they sometimes called?

A flexible tank is a reinforced rubberized bag installed in a section of the aircraft structure. They are sometimes referred to as fuel bladders or bag tanks.

Why are flexible tanks often used in high-performance light aircraft and military aircraft?

Flexible tanks are often used in high-performance light aircraft and military aircraft because they are less likely to split on impact and can be effectively self-sealing in the event of minor battle damage.

What is the purpose of baffles fitted inside larger aircraft fuel tanks?

Baffles are fitted inside fuel tanks to restrict the movement of the fuel and minimize the large inertial forces generated when the fuel surges during aircraft maneuvers.

What are baffle check valves and how do they function?

Baffle check valves allow fuel to flow inboard but restrict its flow outboard towards the wingtips during maneuvers, helping to control fuel movement within the tank.

What additional components are found in aircraft fuel tanks, especially in larger aircraft?

In larger aircraft, fuel tanks also incorporate vents, a gauging system, water drains, filler caps, booster pumps, low-level float switches, and pressure refueling valves.

Why are vents and water drains important in aircraft fuel tanks?

Vents are important for allowing air to escape as fuel is added, preventing overpressurization, while water drains are used to remove any water that may accumulate at the bottom of the tank, which can contaminate the fuel.