Aircraft Axle Jack Repairs

tronair ground support equipment training

Aircraft jacks are an important part of any ground support maintenance program. While some aircraft jacks are interchangeable for various aircraft in some cases correct pads are required for a specific aircraft model.

 

One of the most common types of aircraft jacks used in the industry is the axle jack.  An axle jack is used for aircraft maintenance involving wheel replacement, brake repair, and other maintenance procedures when lifting the nose and/or main landing gear is required.  Axle jacks are placed directly under aircraft landing gear to lift it off the ground.

 

Axle aircraft jacks are somewhat different from other aircraft jacks they are not used to lift the entire aircraft but lift only the wheels. They are used when maintaining or repairing the wheels, tires, brakes, or struts, etc. For repairs on these parts, it is not necessary to lift the entire aircraft.

 

There are three types of axle aircraft jacks. These are hand-carried type, the horseshoe, and the outrigger. Hand-carried axle jacks are lightweight devices and have manually operated hydraulic pumps. Horseshoe axle jacks are much heavier and have an arm powered by two hydraulic cylinders. The outrigger axle jacks are the heaviest and have a hydraulic cylinder powered by a two-speed pump.

 

Check your jack before use

 

Aircraft jacks should be fully checked by running them up and down before using them on an aircraft., You should fully inspect the jacks before each use to ensure they are still in operational order.

 

Following five-point inspection check is most commonly recommended:

 

If the aircraft jack does not pass this inspection check fully, do not use it as any further use may worsen the damage to the jack, or the jack could fail and cause costly damage to the aircraft or even injury to workers. A robust preventative maintenance program keeps your jacks in top working condition and reduces downtime when they require repairs.

 

Indications that the jack needs maintenance

 

Maintenance issues can compromise the functionality of the axle jack to operate efficiently. If the jack  exhibits the following signs, then repair the jack before use:

 

Hydraulic jacks depend on fluid-driven pressure to create movement. When the flow is compromised, it can cause problems with lifting mechanisms.

Excessive noise coming out from the wheels indicates that they should be replaced or repaired.

Check if the mechanical structure of the jack is sound, otherwise, the entire unit could fail under a heavy load. Such damage cannot be repaired and the jack has to be discarded.

Milky or frothy oil means that water has contaminated the hydraulic system. This must be remedied quickly, otherwise, it will cause irreversible internal corrosion of the jack.

If the handle kicks back up after a downstroke then do not use the jack. This condition is quite dangerous for operators as it may injure them. The malfunction should be checked and repaired.

If there is fluid leaking from the unit is a sign that could indicate a range of potential problems. A thorough examination of the unit is necessary to resolve the issue.

When rams of jack do not respond properly, it means a low hydraulic fluid. Check for fluid level and add more fluid if necessary. Turn the jack to its release position, pump a few times to release trapped air, and then refill the reservoir.

If the load is above the capacity of the jack, then the jack’s safety valves will open and the jack will stop working.  Reset the safety valve and avoid overloading the jack.

 

Troubleshooting and repairing an aircraft axle jack

 

You should start by cleaning the jack by removing all debris, dirt, and any other gunk. Use a metal bristle brush, and a rag to clean it. Remove as much dirt as possible. In many cases, you may find the grime and dirt were the things causing the problem.

After cleaning the jack, then you should test the cylinder plug. it is located on top of the cylinder that pushes the fluid. Check that it is not broken or loosened up. If it is broken or damaged, then replace it.  Before putting it on, be sure to clean it thoroughly. Put it back on the right hole and then press it firmly. The plug should fit flat on the hole.

Check if the fluid is not milky or dirty. If some dirt has gone into the fluid chamber it may cause the fluid to not work. Check if there too little or too much fluid. Either way, drain out the fluid. And pour only the right amount back into the jack. If the fluid is too dirty or milky, then replace it entirely.

if there’s too much fluid on the jack then the release valve may be releasing too much pressure when you’re lifting. In such case the unit will release the pressure automatically. However, in most cases, this happens only if the release valve is faulty or damaged.  Either way, check if the valve is loose then there’s a good chance that it will leak. If it is damaged, replace it.

After draining the hydraulic fluid and replacing the rubber plug, you may have let some air go into the jack. This may also cause a loss of pressure. To fix it, you just need to bleed it out. Retract the release valve and then pump the handle several times. Any air inside the jack will go out this way. Put the release valve in the normal position and check if it works.

 

Before you go and lift anything following the above steps, test it out first. Lift the arm and then bring it down several times. This should let you know if the problem persists. If after several tries you still see no problem, test it with a vehicle.

 

e2b calibration can maintain and service all types of aircraft jacks to the highest industry standards while being reliable and cost-effective. Our verifiable services are unmatched in the industry. We are registered with ANAB. We are also ANSI/NCSL Z540-1-1994 certified. We have the NIST Traceable Wide scope of ISO/IEC 17025 accreditation. Contact e2b calibration for more information about our on-site services.

 

AIRCRAFT JACK PROOF LOAD TESTING GUIDE

The ultimate guide to understanding aircraft jack proof load testing.