3.2 Aircraft Systems

The Hydraulic System

 

Aircraft utilize numerous systems in order to function precisely, efficiently, and most of all safely. Today we are going to discuss the hydraulic system, in the 1930s these systems became operable in the actuation of retractable landing equipment. (Wang, S., Tomovic, M., & Liu, H., 2015) Simple approaches contain at least a reservoir, a pump, a filter, a control valve, a relief valve, and an actuator. (Federal Aviation Administration, 2016) This system is responsible for several applications centered around the design complexity of the aircraft. Common aircraft functions include the actuation of wing flaps and slats, wheel brakes, maneuvering systems, and the extension and retraction of the landing gears.  (Federal Aviation Administration, 2016)

 

According to Michele Baker at York Precision Machining and Hydraulics, the most common causes of hydraulic system failures are Air/Water contamination, Temperature complications, Fluid Levels/Quality and Human Errors. (2020) Contamination is the leading cause of failure at 80-90%, which can be caused by faulty pumps, temperature issues, or even system breaches. (Baker, 2020) Something to keep in mind is that human error can play a huge role in the contaminating of these systems, incorrect installation due to misinterpretation of manuals or incorrect parts to lack of maintenance can be the result of human error. These failures can cause injury, damage, or worse a fatal aircraft accident. Devotion to detail and the anticipation of risks are crucial in all phases of safety.

 

A hydraulic failure incident with a T-38C Talon on November 20, 2017, in Texas, took the life of Captain Paul J. Barbour. Oriana Pawlyk reported that the jet had experienced a dual gearbox and hydraulic pump failure, causing a total system failure. The Air Force investigation board stated that the substantial contributing factor was a lack of maintenance guidance addressing similar repeated failures. (Pawlyk, 2018) The gearboxes had 13 total previous failures.

 

Centered on this hydraulic system criticalness, many design elements are integrated to ensure reliability, repetition, and the ability to retain control of the aircraft in the occurrence of one or more malfunctions. (Skybrary, 2020) Usually, aircraft systems are built with redundancies in the event of and to mitigate any failures that may arise. Routine maintenance, strict adherence to manuals and specifications, dedication to detail, and following all checklists will reduce the occurrences of failure in aircraft systems.

 References:

Baker, M. (2020, February 13). Most Common Causes of Hydraulic Systems Failure: YorkPMH. York Precision Machining and Hydraulics. Retrieved from https://yorkpmh.com/resources/common-hydraulic-system-problems/#:~:text=Common%20Causes%20of%20Hydraulic%20Failure%201%20Air%20and,Levels%20and%20Quality.%20...%204%20Human%20Error.%20.

Federal Aviation Administration. (2016). Pilot's Handbook Of Aeronautical Knowledge, FAA-H_8083-258. 2016. Retrieved from https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/pilot_handbook.pdf

Pawlyk, O. (2018, August 23). Total Hydraulic Failure Caused Deadly T-38 Crash in November, Air Force Says. Retrieved from https://www.military.com/defensetech/2018/08/23/total-hydraulic-failure-caused-deadly-t-38-crash-november-air-force-says.html.

SKYbrary Wiki. (2020, March 14). Hydraulic Problems: Guidance for Flight Crews - SKYbrary Aviation Safety. Retrieved from https://www.skybrary.aero/index.php/Hydraulic_Problems:_Guidance_for_Flight_Crews.

Wang, S., Tomovic, M., & Liu, H. (2015). Chapter 2 Aircraft Hydraulic Systems. In Commercial Aircraft Hydraulic Systems (p. 53). essay, Academic Press Inc.