Electric landing gear strut maintenance encompasses checks on motor performance, external parts, lubrication of the moving parts, checks on aging of the electrical circuit, and periodic load tests. Scientific testing and maintenance effectively reduce failure rates while extending service life and enhancing operational safety and efficiency.
Motor Maintenance
The rated power of high-quality electric landing gear strut motors is generally in the range of 50W-300W, with the response time of the control system not more than 200 milliseconds for an accurate operation. If it takes longer than 500 milliseconds, the equipment will delay or fail to work, and the control module should be replaced or calibrated immediately.
How to detect motor operational stability:
- Vibration frequency detection: The operating vibration frequency shall not exceed the range of 5-10Hz. Frequencies higher than this range may indicate worn-out bearings.
- Noise level test: Noise of the motor should not exceed 50 decibels. Irregular noises, such as sudden sharp sounds, reflect internal component failures in the motor.
For the purpose of prolonging equipment life, equipment with high-frequency usage, operating for more than 500 hours every month, is examined monthly, while those at a normal usage frequency are checked every three months.
To reduce amplitude to 10% of rated current for stable motor output, current fluctuations are tapped onto high-precision testers. Data indicates that regular tests produce a 20%-25% reduction in operational failures and about a 15% reduction in annual costs.
External Part Inspection
Ensuring the integrity of external parts is one of the most fundamental issues in the safe operation of electric landing gear struts. The operational risks increase significantly, especially under high-frequency conditions, if the proportion of missing components exceeds 1%. Commonly missing parts include fastening bolts, support pads, and external guards, which can usually be identified through visual checks and tool measurements.
Detection methods:
- Missing part inspection:
- Standard parts checklists will be applied for piece-by-piece inspection to ensure that no critical components are missing in the equipment.
- Electronic inspection devices can substantially improve detection efficiency, permitting approximately 200 components per hour with a minimum level of human error.
- Deformation detection:
- Measure straightness and dimensional deviation of main components (support rods) to a maximum of 0.5 millimeters.
- Put standard loads on the supporting parts, such as 500 kilograms, and see if there is any abnormal deformation under the load.
Inspection Cycle:
- The important external parts will be inspected once every six months; for those parts that have gone through bad environmental conditions, such as high humidity or big differences in temperature, it will be shortened to three months.
- Dimension and bolt fastening torque are within the normal range. It usually ranges from 10 to 50 Nm.
By implementing rigorous external part inspection procedures, unplanned downtime may be reduced by up to 30%, thus elongating the life of the equipment by about 15% effectively.
Lubrication Check
Poor lubrication or lack of it enhances friction by 25%-40% and increases failure rates by 35%. This warrants periodical checks on the condition of lubrication.
To determine whether the oil has dried, observe its surface for clumping or adherence of particles. Oil viscosity must remain within 100cSt±10% at 40°C. Excessive viscosity increases energy consumption, while low viscosity reduces lubrication effectiveness. Quick tests can be conducted using a viscometer, producing results in just five minutes.
Oil quality testing concerns oxidation resistance, high-temperature resistance, and the content of particles. The lubrication performance of such oils decreases by 30% if, after 200 hours of continuous work, they do not pass oxidation tests. Also, an increased particle content of over 1000 particles larger than 10 microns per liter may lead to a dramatic rise in bearing wear and its imminent replacement.
Devices with higher operational frequency should check the oil every 1,000 hours of operation or after three months. Equipment in a high-temperature environment—temperatures starting from more than 50°C—should have shorter inspection intervals, such as one month. Use high-quality oil replacement products according to ISO VG 100, whose operating temperature ranges from -10°C to 120°C for best performance.
It can lessen friction by 15-20%, raise the operation effectiveness by 8-12%, and expand the service life of some critical components by more than 20% if regular lubrication check and change are made.
Circuit Inspection
The circuit condition is a main problem affecting electric landing gear struts during safe operation. The circuit aging or exposure of the metal accounts for 40% according to the statistics, where most faults come out from the damage of insulation layer and loose joint.
Circuit aging can be detected if wire surfaces show discoloration, cracking, or hardening. The wires are usually of high quality and could last 5-10 years under normal conditions, but they will degrade to 3-5 years when the environment has over 80% humidity or temperature fluctuates frequently, for example, from -10°C to 50°C. The potential aging issue can be identified by regular infrared thermometry. The circuit surface temperatures more than 20% over ambient indicate possible hazards.
The main occurrences of exposed metal are usually found in the joint area of cable joints or bent sections of harnesses. Joint areas take 60% of the occurrences of exposed metal. Dielectric strength tests using a high-voltage tester ensure insulation strength, with a guarantee of the standard value of 1000V/1 minute without breakdown, effectively finding out risks.
Recommended inspection cycles:
- Insulation integrity is usually inspected every six months, particularly in high-humidity or dusty environments.
- Conduct comprehensive circuit testing every 12 months, including continuity, load capacity, and insulation resistance (resistance should exceed 10MΩ).
Repairing aging or exposed circuits can reduce short-circuit risks by over 50% and extend the overall system lifespan by approximately 15%. Keeping connection terminals dry and tightening joints regularly further improves equipment stability and reduces failure rates.
Load Testing
Load testing has ensured that electric landing gear struts can withstand operational pressure and provide stable performance. It has been recorded that not carrying out regular load tests results in 30%-40% of all possible faults going undetected, especially in high-frequency applications.
Load testing simulates the maximum operating conditions. Standard practices include gradually increasing the load to 80%-100% of the design capacity and observing operational stability and structural changes. The maximum load-carrying capacity for most general struts ranges between 500 kg and up to 2 tons. During the test, whether the lifting speed is within the rated range, such as 0.5 m/s ± 10%, should be checked.
Key parameters to be checked during tests:
- Motor performance: Ensure stable current output, with fluctuations not exceeding 10% of the rated value.
- Mechanical component status: Detect any bending or permanent deformation of support rods. If deformation exceeds 0.1 millimeters, replace or adjust immediately.
Recommended test frequency is every six months. For devices operating over 500 hours per month or in high-load environments, the cycle should be reduced to three months.
Practical data indicate that regular load testing decreases unplanned failure rates by 25-30% and improves general operational efficiency greatly. Maintaining detailed test records allows for tracking performance trends, anticipating potential problems, and reducing long-term maintenance costs.
