Abstract
The potential of the modern transport aircraft has been seen on the runway and in the air. One of the most challenging and important aspects of aircraft performance is brake systems. This paper explores the most common braking faults of transport aircraft and their causes. The eight major brake fault categories are analyzed and discussed: poor brake performance, brake overheating, runaway brakes, brake wear, brake seals failure, brake pressure loss, pollution, and overlap brake faults. Each has causes and remedial actions. The paper considers a wide range of issues incidental to braking. For each, there is a discussion of fault root causes in addition to specific hardware and systems failures. Finally, the paper discusses the impact of these issues on brake system maintenance and operation.
Introduction
The modern transport aircraft carries passengers and cargo over an increasingly long range. To do this successfully requires aircraft to be capable of landing safely and efficiently. To a great extent, the performance of an aircraft on the runway relies on the performance of its brakes. This paper explores the common brake faults of modern transport aircraft and their causes.
Brake Performance
Poor brake performance is a major brake fault that affects modern transport aircraft. It typically occurs when there is a difference between the actual and expected brake capacity during takeoff or landing operations. This poor brake performance can be caused by a number of issues, including dust and debris build-up on brake pads, worn brake pads, incorrect pressure settings, contamination of brake fluid, and other mechanical damage. Poor brake performance can also be caused by a lack of brake fluid, an improperly set pressure bleed valve, or a braking system that is not sufficiently pressurized.
Brake Overheating
Brake overheating is a common brake fault that occurs as a result of excessive stopping force. This excessive force causes the brake mechanisms to heat up more than they should, resulting in damage to brake systems, tires, and even the aircraft structure. Overheating of the brakes can be caused by a number of factors, including lack of lubrication and excessive drag. Poor braking technique and using excessively hard braking can also cause brake overheating.
Runaway Brakes
Runaway brakes is a major brake fault that occurs when the brakes are applied but do not release as expected. This problem can be caused by a number of mechanical issues, including a sticking brake caliper or a seized brake line. Other causes of runaway brakes include problems with the anti-skid system or a failure of the hydraulic pump. In some cases, it can be difficult to identify the exact cause of the runaway brakes and diagnosis can require the use of specialist instrumentation.
Brake Wear
Brake wear is a common fault of transport aircraft brake systems. Brake wear can be caused by a number of issues, including incorrect brake plate torques, incorrect wheel alignment, or excessive friction between the brakes and the wheel. Brake wear can also be caused by a lack of lubrication, improperly adjusted brakes, or excessive wheel loads.
Brake Seals failure
Brake seals are an important component of transport aircraft brakes, as they prevent dirt and debris from entering the brake system and potentially causing damage. However, they can fail due to a number of causes, including incorrect installation, corrosion, or age. Sealing ring corrosion is particularly common, as the rings are subject to much wear and tear and can be damaged by exposure to air, water, and other substances. Additionally, seals can crack or break due to fatigue.
Brake Pressure Loss
Brake pressure loss is a fault that occurs when there is a drop in brake pressure, resulting in inadequate braking power. This fault can be caused by a number of issues, including incorrect pressure settings, a worn or damaged brake pressure regulator, or a blocked brake line. Additionally, brake pressure loss can occur when the brake fluid level becomes too low, due to a leak or incorrect maintenance of the brakes.
Pollution
Pollution is another common brake fault that affects modern aircraft. This occurs when debris from the runway or tarmac becomes embedded in the brake pads, resulting in poor performance. This dirt and debris can worsen braking performance and increase the risk of brake failure. The best way to prevent this type of brake fault is to ensure that the brake pads are regularly inspected and cleaned.
Overlap Brake Faults
Overlap brake faults occur when the position of the brake pads is incorrect, resulting in them not releasing correctly. This can be caused by a misalignment of the brake pads, incorrect installation of the pads, or a worn cam ring. Overlap brake faults can also occur due to incorrect maintenance of the brake system, such as a failure to replace worn brake pads or an accumulation of dirt and debris on the brake pads.
Conclusion
The performance of the modern transport aircraft relies heavily on the performance of its brakes. While there are a number of potential brake faults that can affect aircraft, this paper has explored the eight most common brake faults and their causes. Poor brake performance, brake overheating, runaway brakes, brake wear, brake seals failure, brake pressure loss, pollution, and overlap brake faults are all common problems that can affect modern transport aircraft. Each of these faults has a range of causes and requires specific action to correct it. Understanding the causes of these faults is essential for safe and efficient aircraft operations.
