Aircraft Jacks – how to find the leak in their hydraulic system?

Aircraft jack is an important part of ground support equipment that is used to service and maintain aircraft. There are four basic types of hydraulic aircraft jacks, the two main ones are the tripod and axle jacks while the remaining two are bipod and quadruped jacks.

Tripod Aircraft Jacks

Tripod aircraft jacks can be used to lift an entire aircraft for service and repair. These jacks have th

ree sturdy legsand that is why they are called tripods. A tripod jack is also portable, self-contained, with a tubular steel structure mounted on caster wheels. Their main components are a hydraulic cylinder connected with a pump assembly in the middle.

However, these types of aircraft jacks should not be used to lift a part of an aircraft if it is not on an even plane as the lateral force can damage the jack. This type of movement may occur when raising the aircraft to change a wheel that has deflated.

Axle Aircraft Jacks

Axle aircraft jacks are a bit different than the tripods as they are not used to lift the entire aircraft but they are usedto lift only a certain part of the aircraft such as the landing gear, to repair or replace the tires, axles, wheels, brakes, or struts, etc. For such repairs, it is not necessary to lift the entire aircraft. They are functionally similar to a jack you would use to change the wheel of your car.

Five-Point Aircraft Jack Inspection

All hydraulics jacks are rugged devices however since they sustain heavy loads, therefore always remember to inspect the jack before each use. Here is a five-point inspection checklist that is most commonly recommended before using an aircraft jack:

• Check the hydraulic fluid levels carefully, as low levels can cause jack failure.
• Check if any part of the jack is bent or stressed.
• Check the joints, if they show any signs of strain or cracking.
• Check the condition of the locknuts and ensure if they are secure.
• Check for any other missing or damaged components.

If the aircraft jack does not pass this inspection checklist, do not use the jack, as it may damage the aircraft or cause injury to the workers. A good preventative maintenance program is necessary to ensure so your jacks remain in perfect working condition with minimum downtime.

Common Hydraulic Jack Problems

Here are the most common aircraft hydraulic jack problems that you may encounter:

• Hydraulic oil is leaking.
• Rams won’t lift.
• Jack is drifting down slowly or is not extending completely.
• The frame construction seems weakened or damaged.
• Wheels squeak when moved, don’t roll properly, or are completely jammed.
• Jack handles kickback to the operator.
• The oil is of milky color and maybe foaming, indicating contamination.
• Overload safety valve tripping without any apparent cause.

Signs that Indicate Hydraulic Jack Repair

There are no visual indications to alert operators or technicians of the oil leak until system performance appears to be severely degraded. The problem often remains undetected for a long time. When a repair when done, it is often unplanned, on an emergency basis, and is never optimal. If the problem had been caught during routine planned maintenance then earlier, it would likely have been repaired more easily and in a better way during planned downtime, without any loss of productivity.

How to Detecting External Hydraulic Leaks Faster

There can be different ways to detect and locate an external oil leak quickly, saving both time and money.  The faster a leak is identified and reported, the more time you have to respond before it shows significant loss of performance and long-term damage to your hydraulic equipment.

Use Hydraulic Oil with a Distinctive Color

It is often difficult for the operators and maintenance staff to identify a hydraulic leak. Consider using hydraulic oil that has a different color as compared to the other lubricants and fluids used around the area. It becomes easy for operators to detect a different color oil leak. This can help the technicians to quickly identify when a leak is in the hydraulic system and it is repaired before it becomes a serious issue.

Internal Hydraulic Leaks

Internal hydraulic leaks are not visible, nor they are necessarily bad. Small internal leaks are accepted and allowed by the manufacturer.  Such internal leaks typically occur through small pathways so that the oil seeps through from higher pressure to a lower pressure zone. It helps to lubricate, clean, and cool a specific part of the jack.

These planned internal leaks do not let the fluid exit the hydraulic circuit, so there is no visual indication of their presence. However excessive internal leak due to wear and tear of the operating surfaces during normal operation is not good. Excessive leakage can be from bad design, wrong component selection, or poor quality of manufacture of the jack.

Detecting Internal Hydraulic Leaks

To detect internal leakages, flow meters are installed at various locations such as drains of pumps and motors. This helps in determining when an overhaul of these components is due before performance is degraded severely.

Manufacturers recommend an optimum operating viscosity necessary for the equipment to perform within the design parameters. Selecting a fluid and maintaining an operating temperature that achieves the recommended viscosity is the responsibility of the equipment user.

Temperature measurement at the critical components ensures that the equipment is operating within that optimum range. Infrared thermometers are useful measurement instruments to check the operating temperatures of equipment. An abnormal temperature increase indicates a problem and should be investigated immediately.

Using Ultrasonic Tools for Hydraulic Leak Detection

Ultrasonic detection is another effective method of determining high-pressure leaks in various locations of the valve and cylinders. This method helps to determine the location of the internal leakage, however, it is not quantitative. The only quantifiable method is to measure the amount of flow or quantity of fluid that has leaked in a particular time by using a flow meter.

Aircraft jacks are a vital part of any aircraft ground support program. We repair all kinds and sizes of hydraulic aircraft jacks. e2b calibration is an ISO/IEC 17025:2017 accredited laboratory. We specialize in cost-effective repair and maintenance services of all types of hydraulic systems. We are registered with ANAB. We are also ANSI/NCSL Z540-1-1994 certified. Please contact e2b calibration for preventive and maintenance services for your ground support equipment.