Structural Aircraft On Ground Repair: Faster, Compliant Return to Service.

Why AOG happens (season by season).
Aircraft on Ground (AOG) events spike for different reasons across the year. In spring, migrating wildlife increases bird-strike risk during daylight hours, prompting inspections and occasional structural work before dispatch.

In summer, deep convection drives thunderstorm hazards—hail, lightning, turbulence, and high-altitude icing—that can mar radomes, nacelle inlets, and leading edges or trigger precautionary checks.

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In winter, ramp contamination and de-icing operations add complexity. Holdover-time planning helps, but changing precipitation and temperature still lead to findings that keep aircraft on the ground.

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Year-round, ground support equipment (GSE) contact is a major driver of ground damage, often translating into structural inspections or repairs before return to service (RTS).

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This playbook shows how operators and a mobile structural team work as one: what to do before wheels touch down, how to control field variables, and which compliance guardrails keep RTS clean and defensible under Federal Aviation Administration (FAA)/European Union Aviation Safety Agency (EASA) Part 145.

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Before the Team Arrives: Operator Actions That Save Hours

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Stabilize and document (immediately).
Isolate the area so nothing is moved or contaminated. Keep water and humidity out by covering or sealing the site if needed.
Take wide and close photographs that include a measurement scale. If it is safe, note the visible direction of deformation and the suspected direction of impact.

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Assemble one decision packet.
Record the part number and serial number of every affected item. Capture the measured damage dimensions and the exact location.

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Add the most recent maintenance performed and any modifications in the area. Include any preliminary non-destructive testing completed and who performed it.

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List local constraints at the work location: available ground support equipment, electrical power, covered workspace or hangar access, and any airport curfew or similar restrictions.

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Define the time window and access path.
Confirm the “aircraft on ground” priority and describe the operational impact. Summarize current weather observations and near-term forecasts for the airport, noting any resulting limits on ground time.

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Share customs and airport access requirements for outside responders, and provide clear escalation contacts.

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What Changes in the Field (and How We Control It)

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Environment is the first variable.
For composites, protect cure windows with controlled heat, verified vacuum, and heat plots tied to the traveler. For metallics, log fastener/torque evidence and corrosion control as-run—these become part of the Part 145 record.

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Access is the second.
Adapt fixturing, scaffolding, and safety buffers to station realities without compromising the repair scheme. If a step requires a facility asset (e.g., autoclave), plan a split flow to hold the schedule while staying within approved data.

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Inspection closes the loop.
Select NDT to the damage mode: ultrasonic testing (UT) for bond integrity, eddy-current testing (ET) for surface/subsurface on metals, penetrant testing (PT)/magnetic-particle testing (MT) where appropriate—under documented oversight (e.g., EN 4179/NAS410 in EASA contexts).

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Structural Scenarios: Where On-Site Beats Ferry

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Not every structural finding justifies moving the aircraft to a heavy-maintenance facility. The question is whether a safe, compliant repair can be delivered faster and with less operational risk by bringing the team to the aircraft.

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Fuselage and wing skin events

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Typical issues: localized punctures, dents, small nicks, or shallow buckles in fuselage or wing skins.

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Why on-site often wins:

• These defects are frequently covered by the aircraft’s Structural Repair Manual and can be measured and repaired within published limits without complex tooling.
  

• Repairs usually require standard materials, controlled drilling and fastener installation, surface preparation, corrosion protection, and documented inspections—tasks that a mobile structural team can execute reliably at the station.
  

• Avoiding a positioning flight eliminates additional schedule risk, permit needs, and exposure to weather or handling damage during repositioning.
  
  

Decision checks for leaders:

• Measurements confirm the damage is within Structural Repair Manual limits for on-wing repair.
  

• Access to the site is safe and practical using portable stands or scaffolding; no large airframe jigs are required.
  

• The station can provide a dry, clean work area and basic services (cover, power, lighting, calibrated hand tools).
  

• Required non-destructive testing can be performed and recorded on site.
  

• The total time to complete and release the aircraft at the station is shorter than arranging and flying a repositioning sector, securing a slot, and waiting in a queue.
  
  

When to choose a repositioning flight instead:

• Damage exceeds allowable limits or crosses structural joints that require specialized fixtures.
  

• Hidden damage is suspected beyond what on-site non-destructive testing can clear.
  

• The station cannot provide a protected environment (for example, continuous rain with no shelter) and corrosion risk is rising.
  
  

Nacelles and radomes

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Typical issues: erosion, hail impact, minor lightning marks, panel edge damage, small composite or sandwich-panel defects on inlets, fan or core cowls, thrust reversers, or radomes.

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Why on-site often wins:

• Many nacelle and radome repairs are based on well-defined bonded or bolted restoration procedures with clear process controls.
  

• Mobile teams can bring portable heat sources, vacuum equipment, cure monitors, and bond inspection tools to validate the repair process and record evidence.
  

• Completing the repair at the aircraft avoids removing large panels for transport and reduces the risk of additional handling damage or misalignment on re-fit.
  
  

Decision checks for leaders:

• The repair procedure specifies temperatures, pressures, and cure times that can be achieved and logged with portable equipment at the station.
  

• Post-repair verification—such as tap testing or other approved non-destructive evaluation—can be completed and documented on site.
  

• Materials with the correct shelf life and storage requirements can be positioned and controlled at the station.
  

• Weather and shelter allow stable temperature and humidity during surface preparation and cure.
  
  

When to choose a repositioning flight instead:

• The repair requires an autoclave or other fixed facility that cannot be replicated in the field.
  

• The geometry or size of the component makes on-aircraft access unsafe or likely to produce marginal bond quality.
  

• The required materials or test coupons are not available within the needed time window.
  
  

Flight-control surfaces

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Typical issues: dents, skin damage, trailing-edge nicks, small composite or metallic defects on ailerons, flaps, slats, spoilers, trim tabs, or the rudder.

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Why on-site often wins:

• Many control-surface repairs can be performed with portable fixtures and then proven airworthy through balance checks and function tests specified in the approved data.
  

• Keeping the aircraft at the station allows immediate coordination between structures, avionics, and operations teams to complete functional checks and return the aircraft to service.
  

Decision checks for leaders:

• The repair instructions include a clear method to verify structural integrity and to perform a control-surface balance check on site (including acceptable ranges and measurement method).
  

• Access allows safe removal and re-installation if required, with the ability to rig and function-test controls per the manual.
  

• Any required non-destructive inspection after the repair (for example, to verify bond integrity or to screen for fastener hole issues) can be completed and recorded at the station.
  

When to choose a repositioning flight instead:

• Balance equipment or control-rigging tooling specified by the manual is not available on site.
  

• The repair area is so constrained that quality or safety would be compromised (for example, near multiple cables, actuators, or high-energy components with limited clearance).
  

• The control surface requires specialized re-balance facilities beyond portable field capability.

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Ferry or Field? A Simple Decision Frame

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Choose on-site when:

• SRM/approved data supports a controlled field process.

• AOG/turnaround time (TAT) pressure outstrips ferry slots or original equipment manufacturer (OEM) queues.

• Weather/shelter allow controlled composite cure or proper metallic protection.

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Choose ferry when:

• Access prevents safe execution, or the environment cannot be stabilized.

• A special process requires fixed-facility equipment by specification.

• Data gaps or airworthiness directive (AD)/service bulletin (SB) constraints mandate OEM paths.
  
  

Document the choice with photos, calculations, and schedule risk—attach to the traveler for audit continuity under Part 145.

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Compliance Guardrails (So RTS Stands Up Later)

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Data first.
SRM, OEM repair, or an approved alternative in hand before touch labor; release paperwork follows the correct procedures for FAA Form 8130-3 or EASA Form 1, as applicable.

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Qualified people.

‍Roles, authorizations, and NDT qualifications are current and recorded (e.g., EN 4179/NAS410 evidence for EASA Part 145 organizations).

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As-run proof.
Cure logs, heat/vacuum traces, torque/fastener sheets, and indication maps are linked to acceptance criteria and retained per Part 145 rules.

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Work away from base.
When maintenance occurs away from the fixed/approved location, follow documented procedures (FAA “work away from station”; EASA 145.A.75(c) “maintenance away from the approved location”).

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Release discipline.
Issue the appropriate RTS documentation—FAA 8130-3/EASA Form 1—per the organization’s procedures and authority.

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On-Site Workflow (Condensed)

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1) Mobilize.
Travel, spares, kits, and calibrated tooling launched with live estimated time of arrival (ETA).

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2) Scope.
Visual plus NDT confirm damage, limits, and the applicable data path.

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3) Execute.
Composite cure or metallic restoration per procedure; deviations documented and re-approved as required.

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4) Validate.
Inspections, NDT, and balance checks where applicable; all findings closed and recorded.

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5) Release.
RTS with the appropriate documentation (FAA 8130-3/EASA Form 1, as applicable) and a complete, audit-ready package; records retained to meet Part 145 requirements.

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KPIs Operators Should Track on Structural AOG

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1. Time to site (call → on-stand) and time to green light (scope complete).

2. Touch-labor hours vs. wait hours (logistics/permits/shelter).

3. Documentation completeness at release (zero post-RTS corrections).

4. Schedule variance against the declared RTS window.

These KPIs justify on-site readiness kits and pre-approved playbooks at leadership level.

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What You Receive (and Why It Matters)

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Traveler/repair pack referencing approved data and final configuration.

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As-run evidence: cure/heat/vacuum plots (composites), torque/fastener sheets (metallics), and NDT reports with indication maps.

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Material traceability (certificate of conformity—COC, batch/lot, shelf-life checks) and photo log.

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Appropriate release documentation (FAA 8130-3/EASA Form 1, as applicable).

This is your audit shield. It speeds internal quality assurance and satisfies authority questions without rework.

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Plan Ahead, Land Sooner

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Structural AOGs are inevitable; missed slots are not.

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Pre-stage a playbook: contact tree, station kits, access badges, and photo/NDT templates. Train operations and the maintenance control center to package the right inputs on the first call.

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When the event hits, a disciplined Structural Aircraft On Ground Repair program turns hours into outcomes: airworthy, compliant, and back on schedule.

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