Hydraulic Leak in Aircraft System

Aircraft hydraulic is a very complicated system with a lengthy plumbings, joints, connections, valves, pumps and so on. As the aircraft aging, especially on component where the seals start to deteriorate, leaks can occur. This is most common findings during routine inspection on aircraft especially in the wheel well area.

Any leakage found should be treated promptly however it is not economical to keep changing any component that have started to leaks. There is an allowable limit set by the manufacturer which allows aircraft that have leakage on its component to be release for flight after details of the leakage been recorded.

In the maintenance manual, the allowable limit basically is how many drop per minute. It further will be specified static or dynamic which is with component is off condition or operational. Aircraft engineers will switched on the relevant aircraft hydraulic system and observed the leaks to find whether it is within limit or not. If out of limit then the component must be changed before next flight.
Not all leakage is allowable, on plumbing connection for example leakage is not allowed at all. With 3000 psi pressure (that is normal operating pressure for most aircraft) any leakage can drain whole system fluid, the good news is that normally there is 2 or 3 independant hydraulic system available on an aircraft so if one system is down, there is still a backup.

All pics sample of leakage is from the aircraft wheel well.


  1. Anonymous said...

    I really liked the easy-to-understand information provided in this context of hydraulic leaks.

  2. Anonymous said...

    helmi..why hydraulic pressure for most of aircraft is only 3000psi? why it's not 2000,4000 or 5000(A380)?

  3. helmis said...

    Very good question, i'm sure my instructor have given me the answer long time ago during my training days but i forgot what is it. What i can say is probably 1. It have been studied/tested that 3000psi is the best/optimum working pressure for acft hyd system. 2. As for standardisation for manufacturing of acft system hyd components, pump, etc by different manufacturer & it can be use on all other acft type/make as well.