Aircraft Hydraulic System Inspection Checklist [FREE PDF]

Aircraft hydraulic systems are critical to flight control, landing gear, and braking operations, requiring rigorous inspection under FAA 14 CFR Part 43 Appendix D maintenance standards. Inspectors must verify fluid levels, actuator integrity, and line condition to prevent in-flight failures. This checklist aligns with FAA and Part 145 repair station requirements to ensure airworthiness and regulatory compliance.

Industry: Aircraft Maintenance
Frequency: Per Event
Estimated Time: 45-60 minutes
Role: Aircraft Mechanic
Total Items: 36
Compliance: FAA 14 CFR Part 43 Appendix D, FAA 14 CFR Part 145.211, FAA 14 CFR Part 43.13, FAA AC 43.13-1B Chapter 9

Hydraulic Fluid Reservoir Inspection

Verify reservoir condition, fluid level, and fluid quality to ensure proper system operation.

Is the hydraulic fluid level within the manufacturer-specified operating range?
Is the hydraulic fluid free of visible contamination, discoloration, or unusual odor?
Is the reservoir cap and filler port seal intact with no signs of leakage?
Is the reservoir pressure (where applicable) within the specified range?
Has the hydraulic fluid type been verified against the aircraft type certificate data sheet?

Hydraulic Lines, Hoses, and Fittings

Inspect all hydraulic plumbing for wear, corrosion, chafing, and secure attachment.

Are all rigid hydraulic lines free of dents, cracks, or corrosion exceeding allowable limits?
Are all flexible hydraulic hoses free of chafing, kinking, or visible deterioration?
Are all hydraulic fittings and B-nut connections torqued and free of seepage?
Are hydraulic line clamps and support brackets secure and free of cracks or corrosion?
Are all hydraulic lines routed with adequate clearance from heat sources and moving parts?
Have any signs of external hydraulic fluid leakage been documented with photo evidence?

Hydraulic Pump and Power Unit

Assess the condition and operation of engine-driven, electric motor-driven, and emergency hydraulic pumps.

Is the engine-driven hydraulic pump free of external leaks at the drive pad and outlet ports?
Is the electric motor-driven pump (EMDP) operational and free of unusual noise or vibration?
Are pump pressure output readings within the manufacturer's specified operating range?
Is the hydraulic pump inlet screen or filter free of debris and blockage?
Is the emergency or standby hydraulic pump system functional and accessible?

Actuators and Flight Control Hydraulics

Inspect hydraulic actuators serving primary flight controls, landing gear, and flight spoilers.

Are all primary flight control actuators free of external fluid leakage past rod end seals?
Is actuator rod end bearing free of play exceeding AMM tolerances?
Are landing gear actuators and downlock mechanisms free of leakage and corrosion?
Are brake actuators and anti-skid system components operating within specified parameters?
Are all actuator attachment bolts and pins within torque specification and properly cotter-pinned or safety-wired?

Filters, Accumulators, and Pressure Relief Valves

Verify condition of system filtration, pressure management, and energy storage components.

Have hydraulic system filters been serviced or replaced at the manufacturer-required intervals?
Is the hydraulic accumulator pre-charge pressure within the AMM-specified nitrogen pressure range?
Is the system pressure relief valve set to the correct relief pressure and free of external leakage?
Are hydraulic system case drain filters inspected and within allowable contamination limits?
Has a photo record been taken of filter condition and accumulator pressure gauge readings?

Hydraulic System Functional Test

Conduct required operational checks to verify full system functionality under pressure.

Has the hydraulic system been pressurized and cycled per AMM functional test procedure?
Did all flight control surfaces respond correctly during hydraulic functional test?
Did landing gear extension and retraction cycles complete within AMM time limits?
Were all system pressure gauges and indicators reading within normal ranges during test?
Was a post-test leak inspection conducted with no new leakage identified?

Documentation and Return to Service

Ensure all inspection findings are properly recorded and the aircraft maintenance record is updated.

Have all discrepancies found during inspection been logged in the aircraft maintenance record?
Have any deferred maintenance items been documented with an authorized deferral reference?
Has the certifying mechanic or repairman signed the return-to-service endorsement?
Have all tools and equipment been accounted for and removed from the aircraft?
Are any additional notes or observations regarding hydraulic system condition recorded below?

Related Aviation Checklists

Related Aircraft Maintenance Checklists

Why Use This Aircraft Hydraulic System Inspection Checklist [FREE PDF]?

This aircraft hydraulic system inspection checklist [free pdf] helps aircraft maintenance teams maintain compliance and operational excellence. Designed for aircraft mechanic professionals, this checklist covers 36 critical inspection points across 7 sections. Recommended frequency: per event.

Ensures compliance with FAA 14 CFR Part 43 Appendix D, FAA 14 CFR Part 145.211, FAA 14 CFR Part 43.13, FAA AC 43.13-1B Chapter 9. Regulatory-aligned for audit readiness and inspection documentation.

Frequently Asked Questions

What does the Aircraft Hydraulic System Inspection Checklist [FREE PDF] cover?

This checklist covers 36 inspection items across 7 sections: Hydraulic Fluid Reservoir Inspection, Hydraulic Lines, Hoses, and Fittings, Hydraulic Pump and Power Unit, Actuators and Flight Control Hydraulics, Filters, Accumulators, and Pressure Relief Valves, Hydraulic System Functional Test, Documentation and Return to Service. It is designed for aircraft maintenance operations and compliance.

How often should this checklist be completed?

This checklist should be completed per event. Each completion takes approximately 45-60 minutes.

Who should use this Aircraft Hydraulic System Inspection Checklist [FREE PDF]?

This checklist is designed for Aircraft Mechanic professionals in the aircraft maintenance industry. It can be used for self-assessments, team audits, and regulatory compliance documentation.

Can I download this checklist as a PDF?

Yes, this checklist is available as a free PDF download. You can also use it digitally in the POPProbe mobile app for real-time data capture, photo documentation, and automatic reporting.