Hydraulic System Failure and Aircraft Performance

The Hydraulic system on an aircraft is very important, as it allows the operation of various aircraft components. A failure of the hydraulic system in the aircraft can have catastrophic consequences and it is one of the most feared events of a pilot when operating a plane. But, there are multiple separate hydraulic systems, usually three, typically installed on an aircraft.

The hydraulic system is used on both small and large aircraft.  For small airplanes, it is used to operate wheel brakes, retractable landing gear, and constant speed propellers.  On other larger planes, it is used for flight control surfaces, spoilers, wing flaps, and other systems (PHAK, 2016). A basic hydraulic system consists of a reservoir, pump (either hand, electric, or engine-driven), a filter to keep the fluid clean, a selector valve to control the direction of flow, a relief valve to relieve excess pressure, and an actuator (PHAK, 2016).  "The hydraulic fluid is pumped through the system to an actuator or servo. A servo is a cylinder with a piston inside that turns fluid power into work and creates the power needed to move an aircraft system or flight control" (PHAK, 2016). The causes of failure in the hydraulic system are leaks, hydraulic fluid contamination, loss of system pressure, or overheating of the system. These can all result in loss of the hydraulic system and the loss of function of those components that it powers (Skybrary, n.d.). The effects of this, according to Skybrary, are anything from loss of control of the plane (to turn right, left, or climb), the inability to retract the landing gear, reduced ability to brake upon landing, loss of anti-skid systems, inability to retract/extend flaps or slats, degraded autopilot performance, among other things. (Skybrary, n.d.). However, a pilot will still be able to land safely

with failure of the system as long as one is functioning, but even then there are still backups in place so a pilot may still be able to land safely or have a plan of action. But it depends on the aircraft too. This is from my understanding, but I am no pilot.

Although it is rare for a hydraulic system failure to occur, it can happen. Like anything, the smooth and problem-free functioning of the hydraulic systems comes down to regular/periodic maintenance and inspections. If this is done correctly, the hydraulic systems are reliable and this is the only way to minimize risk and ensure proper operation. 

References for images:

Cahn, L. (2020). 20 Common Myths About Airplanes You Need To Stop Believing. Readers Digest. Retrieved from https://www.rd.com/list/airplane-myths/

Aerospace Engineering. (2019). Aircraft Hydraulic System. Retrieved from http://www.aerospacengineering.net/aircraft-hydraulic-system/

Other references:

Skybrary. (n.d.). Hydraulic Problems: Guidance for Flight Crews. Retrieved from https://www.skybrary.aero/index.php/Hydraulic_Problems:_Guidance_for_Flight_Crews

Federal Aviation Administration. Pilots Handbook of Aeronautical Knowledge (PHAK). (2016). Retrieved from https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak

Aerospace Engineering. (2019). Aircraft Hydraulic System. Retrieved from http://www.aerospacengineering.net/aircraft-hydraulic-system/