.png){kind=small}
Types of Aircraft Jacks and Jack Testers in Aviation
- ADMIN
- Sep 24
- 5 min read
Updated: Sep 29
Aircraft jacks come in several types, each serving a specific purpose. Tripod jacks, with their three-legged structure, are used to raise the entire aircraft for landing gear retraction tests, structural checks, or heavy maintenance. Axle jacks are smaller, portable units designed to lift individual gear legs for wheel and brake changes, while strut jacks allow technicians to compress or extend oleo struts during servicing. Auxiliary jacks, such as wing and tail jacks, stabilize the aircraft during lifting to prevent tipping, while low-profile floor jacks provide access in tight spaces, particularly on regional or business aircraft. Capacities range from a few tons for light applications to over 200 tons for wide-body jets.
To guarantee safety, jacks themselves must be verified with jack testers. These specialized machines apply controlled loads to confirm that each jack can support its rated capacity and withstand proof loads of up to 110%. Universal jack testers feature adjustable frames, high-strength locking systems, and certified load cells with digital readouts for accurate measurement. Testing ensures hydraulic systems, relief valves, and mechanical locks function as designed. Regulatory bodies such as FAA, EASA, and IATA require regular proof load testing, making jack testers essential for compliance and reliability.
Introduction to Aircraft Lifting Systems
Aircraft lifting systems are a cornerstone of ground support operations, enabling technicians to safely perform inspections, repairs, and scheduled maintenance tasks. Unlike standard lifting tools, aviation jacks are engineered for loads that can exceed 100 tons, while maintaining millimeter-level precision to protect the aircraft structure. Every jack must align with OEM-specified jacking points, which are reinforced locations on the fuselage or landing gear designed to carry concentrated loads. Lifting an aircraft is never a simple act; it requires calculations of the center of gravity, wind load, and the effect of shifting weight when systems such as landing gear or fuel tanks are serviced. The entire operation is regulated under strict safety procedures, and the lifting equipment itself is subject to international standards such as FAA AC 43.13, EASA Part-145, and IATA/AHM guidelines.
Aircraft Tripod Jacks and Their Functionality
Tripod jacks are the workhorses of full-aircraft lifting operations. Their design includes a triangular three-leg base that distributes load evenly across the floor surface, a central hydraulic cylinder to provide vertical lift, and an interchangeable head that matches aircraft jacking pads. Capacities vary widely, from 5–15 tons for regional jets to 150–200 tons for wide-body aircraft like the Boeing 777 or Airbus A350. During landing gear retraction tests, multiple tripod jacks are positioned simultaneously, often four to six units around the aircraft, and are extended in synchronization using hydraulic manifolds to ensure balance. Mechanical collars or screw locks are engaged once the required lift height is reached, securing the load mechanically in case of hydraulic pressure loss. Tripod jacks are also fitted with safety bypass valves to prevent over-extension and load-holding valves to eliminate uncontrolled descent. Their ability to lift an entire aircraft makes them essential for heavy maintenance checks and structural work.
Axle, Strut, and Auxiliary Jacks
Axle jacks are compact, portable hydraulic jacks designed to lift one landing gear leg or axle at a time. They are heavily used in line maintenance for wheel and brake changes, with capacities typically in the 5–30 ton range. Most axle jacks include built-in wheels and handles for portability across the ramp and hangar, and many are fitted with dual hydraulic systems (manual pump and pneumatic pump) for redundancy. Strut jacks, in contrast, are specialized tools for compressing or extending oleo-pneumatic landing gear struts during servicing. They ensure that nitrogen and hydraulic fluid inside the strut are properly balanced, which is critical for correct damping during landing. Auxiliary jacks such as wing and tail jacks prevent instability when an aircraft is raised on tripod jacks; without them, a shift in the center of gravity could cause the aircraft to tip. Low-profile floor jacks are another subtype, designed to fit under tight clearances, particularly for business jets or when tires are deflated. Each of these jack types plays a targeted role in keeping maintenance efficient and safe.
Engineering Considerations and Safety Mechanisms
The engineering design of aircraft jacks reflects both structural and operational safety requirements. Structural frames are typically fabricated from high-strength carbon steel or aerospace-grade alloys, providing high yield strength and fatigue resistance over repeated load cycles. Welds are non-destructive tested (NDT) to ensure integrity under maximum rated loads. Hydraulics are engineered with multiple redundancies: dual check valves to prevent backflow, relief valves to avoid overpressure, and venting systems to remove trapped air. Mechanical safety collars, often threaded or ratchet-based, lock the load mechanically so that the jack can hold the aircraft indefinitely without relying on hydraulic seals. Ground stability is another critical factor — base plates are designed with wide footprints or can be extended with stabilizer arms to handle wind gusts or uneven floors. Operators must also calculate side loads and dynamic forces when moving aircraft components. Every jack undergoes calibration and certification cycles to remain within compliance, ensuring that failure modes are minimized during active maintenance.
Jack Testers and Proof Load Verification
Jack testers are the backbone of ground support safety assurance. These machines apply controlled, measurable loads to verify the rated capacity and mechanical safety of both tripod and axle jacks. Testing is usually required at 100% of nominal load and extended to 110% proof load, simulating conditions that exceed everyday usage to establish structural safety margins. Universal jack testers can handle a wide range of jacks — from light-duty 5-ton axle jacks to 200-ton tripod units. They feature articulated frames to accommodate different jack geometries, high-strength locking pins, and integrated load cells for precise measurement. Modern testers are equipped with digital monitoring systems that log hydraulic pressures, extension rates, and valve performance. Results are printed or exported into digital formats to form part of the equipment’s maintenance records. Regular testing uncovers hydraulic leaks, defective relief valves, or structural weaknesses before they can cause accidents. Aviation authorities mandate jack testing intervals, and documented compliance is a key requirement during audits. In effect, jack testers guarantee that the tools responsible for lifting aircraft remain reliable under all conditions.
Industry Application and Summarization for Aircraft Jacks
Aircraft jacks and jack testers together create a closed loop of operational safety. Jacks provide the lifting capability, while testers validate that the jacks themselves remain within certified performance limits. This dual system protects aircraft, technicians, and maintenance schedules from potentially catastrophic failures. Airlines, MROs, and military operators depend on both categories of equipment, making their selection and testing critical to compliance with FAA, EASA, and IATA standards.
To help illustrate their functions, here is a summary:
Equipment Type | Typical Capacity | Purpose | Common Applications | Testing Requirements |
Tripod Jacks | 5–200 tons | Lift entire aircraft | Landing gear retraction tests, structural inspections | Proof load at 110%, hydraulic check, mechanical lock test |
Axle Jacks | 5–30 tons | Lift individual landing gear | Wheel changes, brake replacements | Load test, pressure holding, valve check |
Strut Jacks | 2–10 tons (varies) | Compress/extend oleo struts | Strut servicing, nitrogen charging | Functional test, calibration of extension force |
Wing/Tail Jacks | Stabilizing loads | Provide aircraft stability | Prevent tipping during tripod jacking | Stability check, mechanical locking |
Floor/Low-Profile Jacks | 5–20 tons | Lift under limited clearance | Regional jets, business aircraft | Load and leak tests |
Jack Testers | 5–200 tons (universal) | Verify jack integrity | Testing tripod and axle jacks | Proof load test, load cell calibration, compliance documentation |
Comments