FAA General Written TestChapter 6 · 40 practice questions

Chapter 6: Ground Operations and Servicing

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Chapter: Ground Operations and Servicing

Overview

This chapter covers the fundamental knowledge and procedures required for safe and compliant aircraft ground operations and servicing. It encompasses the regulatory framework governing maintenance documentation, inspection requirements, ground handling procedures, fueling operations, and the servicing of aircraft systems. Mastery of these topics is essential for aircraft maintenance engineers (AMEs) to ensure airworthiness, safety, and regulatory compliance in all ground-based activities.

Regulatory Framework for Maintenance and Inspections

Return to Service Requirements (14 CFR 43.9)

When an aircraft is returned to service after maintenance, the mechanic must make a complete logbook entry that includes:

  • A description of the work performed (or a reference to data acceptable to the FAA)
  • The date of completion
  • The mechanic's signature and certificate number
  • A statement that the aircraft is approved for return to service

The entry must be specific and clear. Vague descriptions or entries lacking necessary details are not legally acceptable. For example, a minor repair on a flap actuator requires a logbook entry describing the work, the method of compliance, the date, and the mechanic's certification information.

Inspection Requirements (14 CFR 91.409)

The 100-hour inspection is a mandatory requirement for aircraft operated under Part 91 when carrying passengers for hire or providing flight instruction. Key points include:

  • No person may operate an aircraft unless it has received a 100-hour inspection within the preceding 100 hours of operation
  • The inspection must be performed by a mechanic with an A&P rating or an appropriately rated repair station
  • After the inspection, the mechanic must approve the aircraft for return to service and make a logbook entry as required by 14 CFR 43.9
  • All discrepancies found during the inspection must be corrected before return to service
  • A test flight is not required for a 100-hour inspection unless the inspection reveals a discrepancy that requires one

Annual Inspection Requirements (14 CFR 43.15)

The annual inspection follows similar principles to the 100-hour inspection but is required on an annual basis regardless of flight hours. The inspection scope includes all items listed in 14 CFR Part 43 Appendix D, which covers airframe, powerplant, and systems checks.

Major Repairs and Alterations (FAA Form 337)

Major repairs and alterations require special documentation and approval processes:

  • Definition: Major repairs are those that, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness
  • Documentation: FAA Form 337 must be completed for major repairs or alterations
  • Submission: The form must be submitted to the FAA within 48 hours for major repairs or alterations
  • Approval: Major repairs require approval from the FAA or an appropriately rated Inspector Authorization (IA) before return to service
  • Logbook Entry: A logbook entry referencing the Form 337 number must be made

Airworthiness Directives (ADs)

An aircraft with an uncomplied Airworthiness Directive is not airworthy under 14 CFR 91.403. When an AD is discovered during an inspection:

  • The mechanic must either accomplish the AD or ground the aircraft
  • Documentation must be made per 14 CFR 43.11
  • AD compliance must be recorded in the maintenance records
  • Ferry permits are not appropriate for known unairworthy conditions that can be corrected on site

Mechanic Responsibilities and Certification

Mechanics must only certify work that has been completed and found satisfactory. Signing a logbook entry for an inspection that was not performed is a violation of 14 CFR 43.9 and 14 CFR 65.83. This is a federal offense that can lead to certificate action and safety risks. The correct action is to refuse to sign and complete the inspection before signing.

Weight and Balance Procedures

Leveling Requirements

Leveling Requirements - Aircraft Weight and Balance CG Envelope LEVELING REQUIREMENTS — WEIGHT & BALANCE CG ENVELOPE AC 43.13-1B • 14 CFR Part 43 • Level Attitude Required for Accurate CG Determination LEVEL REFERENCE LINE (LRL) TAIL 2" LOW DATUM 620 lb 840 lb 410 lb CG CG ENVELOPE ⚠ CG OUT OF LIMITS MOMENT ARMS SKEWED LEVEL ✓ LEVEL ATTITUDE SHIMS DATUM 625 lb 845 lb 405 lb CG CG ENVELOPE ✓ CG WITHIN LIMITS MOMENT ARMS ACCURATE WHY LEVELING MATTERS — FAA A&P WEIGHT & BALANCE PRINCIPLES 14 CFR §43.13-1B "The aircraft must be leveled in accordance with the manufac- turer's instructions before weighing." CG FORMULA CG = Total Moment / Total Weight A 2" tail-low error shifts CG by up to 3-5% MAC — can move CG outside the envelope. LEVELING METHODS • Spirit level on door sill • Plumb bob from datum • Manufacturer's leveling lugs or jackscrews SkyLicense A&P Prep • Ground Operations & Servicing • Weight & Balance Leveling Requirements

Accurate weight and balance calculations require the aircraft to be in a level attitude to ensure the scales measure the true vertical load at each weighing point. If the aircraft is not level (e.g., tail 2 inches low):

  • Errors are introduced in the moment arms
  • Incorrect center of gravity (CG) calculations may result
  • The aircraft could potentially exceed CG limits

The correct procedure is to level the aircraft with shims and re-weigh to ensure accuracy.

Documentation of Weight and Balance Data

Any major alteration that affects weight and balance requires:

  • Completion of FAA Form 337
  • An entry in the aircraft maintenance records per 14 CFR 43.9 and 43.11

The Pilot's Operating Handbook (POH) is updated, but the legal record is the Form 337 and logbook. This ensures traceability and airworthiness documentation.

Ground Handling and Towing Operations

Towing Preparation

Before beginning any towing operation, the technician must:

  • Verify the tow bar is rated for the aircraft's weight
  • Ensure the tow crew is properly positioned
  • Confirm the nose gear steering bypass pin is installed

The steering bypass pin disconnects the steering actuator from the nose gear, allowing free castering during the tow. Failure to install this pin can damage the steering system. The shear pin is a secondary safety device designed to fail under excessive load.

Towing Procedures

FAA A&P Towing Procedures - Aircraft Ground Operations TOWING PROCEDURES — GROUND OPERATIONS & SERVICING PROPER TOW SETUP TOW steer Tow bar attached to nose gear Shear pin rated for aircraft weight AC 43.13-1B §5-12 TURNING / STEERING 25° Nose wheel steering follows tow vehicle Max turn angle: 25° typical Use tow vehicle steering, not force TOW BAR FAILURE SHEAR PIN FAILED ⚠ AIRCRAFT ROLLING FREE — BRAKE! ✓ Correct: Apply wheel brakes ✓ Chock wheels immediately TOWING SAFETY GUIDELINES — 14 CFR §91.13 / AC 43.13-1B BEFORE TOWING: • Verify tow bar shear pin rating • Confirm nose gear steering bypass pin installed • Check brake system pressure • Ensure tow vehicle capacity sufficient • Walk around — clear all obstacles • Establish hand signals with spotter • Verify wing walkers in position DURING TOWING: • Speed: WALKING PACE only (≤3 mph) • No sharp turns — use wide radius • Spotter maintains visual contact • Continuous communication with crew • Watch wingtip clearance constantly • Avoid sudden stops or starts • Monitor tow bar angle & stress EMERGENCY: • Tow bar failure → BRAKE IMMEDIATELY • Chock wheels before releasing brakes • Signal stop to tow vehicle operator • Set parking brakes if aircraft stopped • Inspect shear pin before re-towing • Report incident per 14 CFR §91.13 • Never try to stop with hands FAA A&P Knowledge — Ground Operations & Servicing | Towing Procedures | AC 43.13-1B Ch. 5 ⚠ SVG-TOW-001 | FAA A&P Exam Prep | SkyLicense

During towing operations:

  • The tow vehicle size relative to the aircraft is not the primary criterion; the tow bar rating is critical
  • Disconnecting the battery is not required for towing and could affect brakes
  • Open doors and hatches are not for visibility and could be damaged

Tow Bar Failure

If the tow bar shear pin fails during towing:

  • Stop immediately
  • Secure the aircraft (chock wheels, set brakes)
  • Report the incident

A failed shear pin indicates excessive tow load or an obstruction. Continuing could damage the nose gear or aircraft structure. A broken tow bar means loss of control; the aircraft must be secured immediately to prevent movement.

Marshaling Signals

FAA A&P Ground Operations - Aircraft Marshaling Signals GROUND OPERATIONS & SERVICING MARSHALING SIGNALS — FAA A&P EXAM PREP COME AHEAD Aircraft taxis forward STOP Aircraft brakes applied TURN LEFT Nose wheel turns left TURN RIGHT Nose wheel turns right CHOCK INSERTION — WHEEL CHOCKS PLACED FOR SAFETY Chocks prevent aircraft movement — AC 43.13-1B / 14 CFR §91.107 FAA-H-8083-30 • AC 43.13-1B • Standard marshaling signals per ICAO Annex 2

The wing walker's primary responsibility is to ensure wingtip and obstacle clearance during ground movement. A stop signal from a wing walker is a critical safety command indicating an imminent collision hazard. The pilot must comply immediately. Clear ground communication and adherence to standard marshaling signals are essential for ramp safety.

Fueling Operations

Fuel Spill Response

Fuel Spill Response Sequence - Ground Operations and Servicing Fuel Spill Response — Ramp Safety Sequence 1. SPILL OCCURS FUEL AVGAS SPILL 2. CONTAIN SPILL KIT / BERM 3. ABSORB ABSORBENT PADS 4. FLAG & CLEANUP ! HAZARD FLAGGED T+0s T+30s T+1min T+2min T+5min REQUIRED SPILL RESPONSE EQUIPMENT (AC 43.13-1B, Chapter 12) SPILL KIT Absorbent pads, booms, pillows PPE Gloves, goggles, apron FIRE EXTINGUISHER ABC-rated, within 50 ft CONTAINMENT Berms, drain covers WARNING SIGNS Flags, cones, placards ⚠ REGULATORY NOTES 14 CFR § 139.321 — Fuel handling and storage; AC 43.13-1B — Fuel system maintenance Report all spills per SOP; large spills require FAA notification and environmental response FUEL FLOW: STOPPED Fuel shutoff valve closed — ignition source secured

Any fuel spill presents a fire hazard and must be addressed immediately. The correct sequence of actions is:

  1. Stop fueling to prevent further spillage
  2. Secure the equipment to prevent ignition
  3. Clean up using approved absorbent materials
  4. Report the spill as required

Continuing fueling or using a dry rag is unsafe and violates standard fueling procedures. Wiping with a dry rag can spread the fuel and create a fire hazard. Solvent dilution is not appropriate, and leaving fuel to evaporate is unsafe.

Fuel Truck Positioning

When positioning a fuel truck near an aircraft:

  • Position the truck upwind to minimize the risk of fuel vapors being blown toward hot engine components or other ignition sources
  • Bond the fuel nozzle to the aircraft to prevent static electricity discharge, which could ignite fuel vapors

Fuel Contamination

Fuel Contamination Detection and Prevention - Ground Operations and Servicing Fuel Contamination Detection and Prevention AC 43.13-1B / 14 CFR §23.975 Fuel Sample Inspection Clear container — let sample settle 5 min Fuel (clear bright) Top layer — acceptable Water (cloudy) ⚠ Contamination! Sediment / debris ✕ Reject sample ACTION REQUIRED If water or sediment detected: 1. Drain sump until clear fuel flows 2. Investigate source — do not dispatch Fuel Truck & Aircraft Pre-Service Check Inspect all points before fueling AVGAS 100LL Fuel port Bond Sump drain Filter Wing sump FUEL QUALITY CHECKLIST ✓ Check truck sump — drain 1 cup minimum ✓ Check filter separator — look for water ✓ Check aircraft sumps — all drains

Water and debris in fuel samples are a safety hazard and a common cause of engine failure. The correct procedure is:

  1. Drain the fuel strainer and all low-point fuel drains
  2. Continue draining until the fuel is clear and free of contaminants
  3. If contamination persists, the aircraft must not be flown until the fuel system is properly serviced or drained

Engine Ground Operations

Reciprocating Engine Oil Pressure Fluctuations

Fluctuating oil pressure, even within manufacturer's limits, can indicate serious problems such as:

  • Faulty relief valve
  • Oil pump issues
  • Oil aeration

Immediate shutdown prevents potential engine damage. Continuing the run-up risks catastrophic failure. Reducing RPM may not resolve the issue, and returning to service ignores a potential safety hazard.

Turbine Engine EGT Limits

FAA A&P Ground Operations - Turbine Engine EGT Limits and Troubleshooting TURBINE ENGINE EGT LIMITS — GROUND OPERATIONS EGT INDICATOR °C EXHAUST GAS TEMP LIMIT 725°C 0 200 400 600 800 742°C EGT EXCEEDANCE ⚠ EGT ABOVE LIMIT (742°C > 725°C) Turbine inlet temp exceeds published limit during ground run. REQUIRED ACTION — DO NOT DISPATCH 1 Reduce power to idle immediately Per AFM / AMM emergency procedure 2 Investigate cause — do NOT dispatch aircraft Check: fuel control, nozzle, thermocouple, engine 3 Record exceedance in engine logbook 14 CFR §91.417 / §121.701 maintenance records TURBINE ENGINE GROUND RUN — EGT MONITORING TURBINE ENGINE IN EXH EGT PROBE EXHAUST GAS FLOW TEMP RISES WITH POWER POWER LEVER IDLE MAX N₂ 85% EGT INCREASES WITH POWER SETTING Reference: FAA AC 43.13-1B, 14 CFR Part 33, Aircraft Maintenance Manual (AMM), Engine Manual

Exceeding Exhaust Gas Temperature (EGT) limits can cause severe thermal damage to turbine blades and other hot-section components. The immediate action when EGT exceeds limits is:

  1. Reduce power to idle
  2. If EGT does not rapidly return to normal, shut down the engine
  3. Document the exceedance per 14 CFR 43.9 and the engine manufacturer's instructions

Turbine Engine EGT Troubleshooting

If EGT is high but N1, N2, and fuel flow are normal, the most likely cause is an instrumentation error, such as:

  • Faulty EGT probe
  • Loose connection

Actual engine problems like FOD, blocked nozzles, or compressor issues would typically affect other parameters (e.g., fuel flow, RPM, or vibrations). Troubleshooting should start with verifying the EGT system.

Fire Protection Systems

Ground operations involving engine runs require that all fire protection systems are fully serviceable. A missing discharge indicator or broken detection loop constitutes a fire protection system malfunction, making the aircraft unairworthy for engine operation. Deferring the test and performing necessary repairs complies with 14 CFR 91.7 and manufacturer's maintenance requirements.

Aircraft Servicing Procedures

Oil Servicing

When adding oil to an engine:

  • Use the correct grade of oil as specified in the aircraft maintenance manual (AMM) or engine manufacturer's instructions
  • Using the wrong grade can cause engine damage
  • Adding oil without checking the manual is unsafe
  • Asking the pilot is not a substitute for technical data
  • Universal oil is not approved for all engines

Oil Level Checks on Warm Engines

Oil expands when warm. A warm engine reading at minimum may actually be at the correct cold level. Adding oil while warm could overfill the system, causing foaming and potential engine damage. Always check fluid levels under specified temperature conditions per the engine manufacturer's manuals.

Landing Gear Strut Servicing

A low strut with correct tire pressure and weight indicates a loss of both nitrogen and hydraulic fluid. The correct procedure is:

  1. Fully deflate the strut
  2. Add hydraulic fluid to the proper level
  3. Recharge with nitrogen to the specified pressure per the maintenance manual

Simply adding fluid or nitrogen without deflating can trap air and create an unsafe condition.

Tire Pressure and Condition

  • The correct tire pressure is specified in the AMM or tire manufacturer's data; the sidewall pressure may differ from recommended operating pressure
  • Over-inflation can cause tire failure; under-inflation can cause excessive wear
  • Exposed fabric or cord in a tire is an unairworthy condition; the tire must be replaced before further flight
  • Inflating to maximum pressure is dangerous and does not fix structural damage
  • Patching is not an approved repair for fabric exposure

Brake Components

Brake discs worn beyond the manufacturer's service limit are unairworthy and must be replaced. Replacement of a brake disc is typically considered a minor repair or preventive maintenance but must be documented in the aircraft maintenance records per 14 CFR 43.9. Sanding or lubricating a brake disc is not acceptable practice and could compromise braking performance.

Oxygen Systems

The green discharge disc on an oxygen cylinder is a safety device that ruptures to relieve pressure in case of overheat or fire. A missing disc compromises system safety. The aircraft is not airworthy until the correct disc is installed.

Deicing Procedures

Deicing fluids can be corrosive to acrylic windshields and may cause crazing or cracking. Standard deicing procedures require:

  • Protecting windshields or avoiding direct application
  • Following the aircraft manufacturer's instructions
  • Using appropriate protective measures

Continuing application is unsafe; using higher concentration or wiping can worsen damage.

Inspection Findings and Corrective Actions

Metallic Particles in Oil Filters

Metallic particles in the oil filter are a serious indicator of internal engine wear or damage, such as bearing or gear wear. Even if engine operation appears normal, continued operation could lead to catastrophic failure. The correct action is to ground the aircraft and perform a thorough inspection.

Control Cables

Control cables with broken wires, even if the diameter is still within limits, must be replaced. Broken wires indicate fatigue and potential failure under load, compromising flight control integrity. This complies with 14 CFR 43.13(a) and manufacturer's maintenance instructions.

Fluid Lines

Fluid lines with damage exceeding allowable limits (chafing, nicks, or corrosion) must be replaced. A 10% wall thickness loss in a fuel line compromises pressure integrity and could lead to a fuel leak and fire hazard. Replace the line and address the chafing cause with a cushioned clamp.

Fasteners

Any fastener showing corrosion, stretched threads, or other damage must be replaced. Reusing corroded fasteners can lead to failure under load, and a stretched bolt indicates over-torque or fatigue. Install new fasteners and torque per the applicable manual.

Pitot-Static Systems

A blocked static port affects pitot-static instruments critical for IFR flight, including altimeter, airspeed, and vertical speed indicators. Operating under IFR with a blocked static port is unsafe and violates 14 CFR 91.7. Clear the port and test the system to ensure accurate instrument indications.

Landing Light Lenses

A cracked landing light lens is a defect that must be corrected to return the aircraft to service after a 100-hour inspection. The lens is part of the airframe, and its failure could lead to bulb damage or foreign object debris. Placarding the landing light inoperative is not allowed because it is required for night flight under 14 CFR 91.205.

Structural Damage

Without approved data or a repair method, the effect of structural damage on integrity is unknown. The mechanic must ensure the aircraft is airworthy before returning it to service. AC 43.13-1B is not a blanket approval without assessing the specific damage per its guidelines. A ferry permit is not appropriate for a known unairworthy condition.

Key Principles and Relationships

Safety Priority

Safety is paramount in all ground operations. When any anomaly is detected:

  1. Stop the operation immediately
  2. Secure the aircraft and equipment
  3. Assess the situation
  4. Report and document

Documentation Integrity

Accurate documentation is a legal requirement, not just a procedural formality. Every maintenance action must be properly recorded with:

  • Description of work
  • Date
  • Signature and certificate number
  • Return to service statement

Manufacturer's Data vs. General Practices

While AC 43.13-1B provides acceptable methods, techniques, and practices, the manufacturer's maintenance manual takes precedence. Always consult the AMM for specific procedures, fluid types, pressures, and limits.

Airworthiness Determination

The determination of airworthiness is based on:

  • Compliance with ADs
  • Completion of required inspections
  • Condition of aircraft components
  • Proper documentation

An aircraft with any known unairworthy condition must not be returned to service until the condition is corrected.

Summary

Ground operations and servicing require a comprehensive understanding of regulatory requirements, safety procedures, and technical practices. The AME must balance operational demands with strict adherence to airworthiness standards. Key takeaways include:

  • Always follow manufacturer's data and approved procedures
  • Never sign off work that has not been completed
  • Address safety hazards immediately
  • Document all maintenance actions properly
  • Consult technical data before servicing any system
  • Prioritize safety over schedule pressures

Mastery of these principles ensures safe ground operations and compliant maintenance practices.

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