General Dynamics Convair 600: Aircraft Jacks

Aircraft jacks are specialized hydraulic lifting devices used to raise and support aircraft during ground maintenance operations. They allow technicians to safely access landing gear components, tires, brakes, struts, and structural systems that would otherwise be inaccessible with the aircraft on the ground. Every category of aircraft – from light single-engine trainers to heavy commercial airliners – depends on proper aircraft jacking procedures for tasks including tire changes, gear retraction tests, strut servicing, aircraft weighing, and major structural inspections. Because aircraft jacks directly support the weight and balance of the aircraft during maintenance, using the correct jack and approved lifting procedures is one of the most safety-critical aspects of aviation ground operations.

The two primary types of airplane jacks used in aviation maintenance are axle jacks and tripod jacks. Axle jacks are positioned under the landing gear axle or strut to lift individual wheels and are the standard choice for tire changes, brake servicing, and wheel assembly removal. Tripod jacks are three-legged hydraulic units designed to lift an entire aircraft or a major structural section from designated fuselage jacking points, making them the preferred tool for gear retraction tests, aircraft weighing, and major structural maintenance. The correct jack type depends on the specific task and aircraft – always consult the applicable Aircraft Maintenance Manual (AMM) for approved jack types, capacities, and jacking point locations before beginning any lift.

Selecting the correct capacity starts with consulting the applicable Aircraft Maintenance Manual (AMM) or Ground Handling Manual, which specifies the approved jacking points, required jack capacity, and lifting sequence for your aircraft. The jack's rated capacity must meet or exceed the portion of the aircraft's weight transferred to it during the operation – for example, when using a three-point tripod jack setup, each jack must be rated for its share of the distributed load. Never estimate jack requirements based on aircraft category alone; always verify ratings against the aircraft's actual maximum gross weight and the AMM-specified jacking procedures. When capacity requirements are unclear, PJi's aviation specialists can assist with jack selection and cross-reference guidance.

Jack pads and adapters are the interface components that fit between the top of the jack and the aircraft's designated jacking point, ensuring secure, load-appropriate contact with the airframe structure without causing damage. Aircraft jacking points are precisely engineered structural locations designed to accept specific forces in specific orientations. Using an incompatible adapter or an unsupported contact area can result in structural damage, hydraulic system punctures, or loss of aircraft stability during the lift. Jack pads and adapters are aircraft-specific, and many are required for both axle jacking and tripod jacking operations. PJi offers a comprehensive selection of aviation jack pads and adapters from Bogert Aviation and other manufacturers, organized by aircraft make – including Cessna, Piper, Beechcraft, Gulfstream, Bombardier, Boeing, Dassault, Embraer, Cirrus, and many others.

Key factors to evaluate when selecting aircraft jacks include lifting capacity, height range, safety features, aircraft compatibility, and overall construction quality. The jack must meet or exceed the weight of the aircraft section being lifted while also matching the aircraft’s approved jacking points and required lift heights. Important safety mechanisms include mechanical lock nuts, overload relief valves, and safety pins that help prevent accidental lowering under load. For operations requiring frequent repositioning, features such as integrated wheels, towbars, or pneumatic pumps can improve efficiency and ease of use in hangars and on ramps.

Aircraft jacks are not universal – different aircraft types have different weight distributions, jacking point locations, structural requirements, and approved jacking procedures that dictate which jack types and capacities are appropriate. Using a jack not rated for the aircraft's weight, or positioning it at an unapproved location without the correct adapter, can result in structural damage or an unsafe lift. Tripod jack requirements, axle jack capacities, and adapter configurations vary significantly between light general aviation aircraft and large commercial platforms. Always consult the aircraft's AMM and confirm the jack, adapter, and procedure are approved for the specific aircraft make, model, and serial number before beginning any jacking operation.

Safe aircraft jacking requires careful preparation, trained personnel, and strict adherence to the AMM and applicable ground handling procedures. Before beginning any lift, the aircraft must be positioned on a hard, level surface with the surrounding area secured, all personnel and equipment clear of the aircraft's movement envelope, and all control locks and gear pins installed as specified. Jacks must be precisely positioned at approved jacking points using the correct pads and adapters for the aircraft, and the lift must be performed in the coordinated sequence specified in the AMM to maintain the aircraft in a level or approved attitude throughout the operation. Hydraulic fluid levels, seal conditions, mechanical locks, and load test currency should all be verified before placing any airplane jack into service.

A jack load test is a periodic proof-of-capacity procedure that applies a calibrated test load – typically equal to the jack's rated capacity plus 10% – to verify the jack can safely support its rated load without hydraulic failure, excessive settlement, or seal leakage. These tests are required by jack manufacturers and aviation maintenance standards at defined intervals, most commonly annually or more frequently for high-use applications, to confirm that hydraulic systems, structural components, and seals remain within specification. Jack load test units are specialized GSE used to apply, measure, and document these test loads in a controlled, traceable manner. PJi provides aircraft jack load test units, along with a full inventory of replacement parts, to support ongoing inspection and compliance requirements.

Aircraft jacks should receive a visual and functional inspection before every use – checking for hydraulic leaks, visible damage to the cylinder or base, fluid levels, and the condition of safety pins, locks, and seals. In addition to pre-use checks, a thorough inspection, including load testing, should be performed at least annually or per the manufacturer's maintenance schedule, whichever is more frequent. Jacks subjected to heavy or frequent use, abnormal operating conditions, or any known impact or overload event should be removed from service and inspected before being used again. Maintaining current inspection and load test records for each jack is an essential part of a compliant, safety-focused ground support equipment program.

A damaged or worn-out aircraft jack typically exhibits one or more of the following indicators: visible cracks, bends, or deformation in the cylinder or base structure; hydraulic fluid leaks around the ram, seals, or hose connections; uneven, jerky, or unusually slow extension or retraction; settlement under load after pumping; unusual noises during operation; corroded or pitted ram surfaces; and malfunctioning pressure gauges or safety valves. Any jack exhibiting these symptoms should be immediately removed from service and inspected by a qualified technician before being returned to use. A jack that has been overloaded, dropped, or subjected to an impact – even without visible damage – should also be inspected before the next use, as internal components and seals can be compromised without obvious external signs.

Aircraft jacks should be stored fully retracted in a clean, dry environment, away from extreme temperatures and direct sunlight that can degrade hydraulic seals and hoses over time. Hydraulic fluid levels should be checked and topped off after each use per the manufacturer's specifications, and ram surfaces should be lightly wiped down and protected against corrosion, particularly in high-humidity environments. Jack pads and adapters should be stored with the jack to prevent loss and ensure they are on hand when the jack is next needed. Periodic lubrication of moving parts and seals, as specified in the jack's service manual, helps extend service life and maintains reliable operation between formal inspection intervals.

PJi carries new and used aircraft jacks – including axle jacks, tripod jacks, alligator jacks, tail stands, and jack load test units – from Tronair, Malabar, Columbus Jack, and Bogert Aviation. Tronair aircraft jacks are among the most widely deployed in commercial, military, and general aviation maintenance worldwide, with a broad product range spanning light aircraft axle jacks through large-capacity tripod and alligator models. Malabar aircraft jacks are a trusted choice for major airlines and MRO facilities, particularly for high-capacity tripod applications, and are known for their robust construction and long service life. Columbus Jack and Bogert Aviation round out PJi's lineup with specialized and general aviation jacking solutions, and PJi also provides a deep inventory of jack parts, seal kits, and aircraft-specific adapters from these manufacturers to support long-term maintenance, compliance, and serviceability.

Modern aircraft jacks include multiple built-in safety mechanisms designed to protect both the aircraft and maintenance personnel during lifting operations. Common features include mechanical lock nuts or locking collars that physically support the load after lifting, overload relief valves that prevent the jack from exceeding its rated capacity, and safety pins or retention devices that help prevent unintended ram movement. Many hydraulic aircraft jacks also incorporate controlled release valves for gradual lowering and wide-base tripod configurations for improved stability. These safety systems are critical for maintaining controlled, secure lifting conditions throughout aircraft maintenance procedures.

Single-stage aircraft jacks use one hydraulic ram section and are generally preferred for applications requiring straightforward lifting at moderate heights. Multi-stage aircraft jacks use two or more telescoping ram sections to achieve greater extension while maintaining a lower closed height, making them ideal for aircraft with limited ground clearance or higher lifting requirements. Multi-stage axle jacks are commonly used on larger business jets and commercial aircraft, where compact storage and extended lifting travel are both important. The choice between single-stage and multi-stage aircraft jacks depends on the aircraft geometry, required lift height, and maintenance application.

Choosing the right aircraft jack starts with identifying the aircraft make, model, serial number, and the specific maintenance task being performed. Technicians must verify the approved jack type, lifting capacity, jacking points, and required adapters outlined in the aircraft’s AMM before selecting any equipment. Factors such as minimum closed height, maximum lift range, portability, and available safety features should also be evaluated to ensure compatibility with the aircraft and maintenance environment. Working with an experienced aircraft jack supplier can help operators identify the correct configuration for both routine servicing and long-term maintenance support.