OSO-03 — Maintenance of UAS

Summary

Defines how UAS designers produce the Instructions for Continuing Airworthiness (ICA) required by OSO#03 and Light-UAS.2625. Covers only the design-related provisions — procedural and staff-training aspects (also part of OSO#03 at medium robustness for SAIL III) are out of scope. The applicant (UAS designer) issues a signed declaration of compliance and provides ICA to operators, who in turn build their maintenance programme on top of it. Pre-/post-flight inspections are excluded (those fall under OSO#08).

Operation Safety Objective

OSO#03 — Maintenance of UAS. Per Annex E to AMC1 to Article 11 of Regulation (EU) 2019/947 and Light-UAS.2625. At SAIL III the requirement is at medium robustness; this MoC addresses only the design-related (ICA) part.

Means of Compliance — ICA Structure

ICA must consist of: 1. Maintenance requirements — exhaustive inventory of scheduled and unscheduled tasks, each tied to an individual maintenance task. 2. Maintenance instructions — how to perform the tasks.

Scheduled maintenance

All tasks with periodic scheduling info.
Must include a segregated "Airworthiness limitations" section.
Typical limitation items: life-limited parts (e.g. batteries) inspections/removals/installations, ageable parts, wiring visual checks.

Unscheduled maintenance

Triggered by undesired events (hard landing, out-of-envelope temperatures, lightning strike, operation outside qualified envelope).
Must include indicative trigger conditions + troubleshooting information (probable malfunctions, recognition, remedial action).
May reference scheduled tasks or use dedicated unscheduled-only tasks.

Maintenance instructions content

Introduction: UA + systems description, schematics for locating parts.
Servicing: tank/reservoir capacities, fluids, pressures, access panels, lubrication points/lubricants, equipment, tow/mooring/jacking/levelling.
Maintenance tasks (per task):
Task identifier (e.g. TSK-XX999)
Title
General description
Task instructions (order, method, precautions)
Scheduling: calendar (HRS/D/Y), flight hours (FH), or cycles (FC); task threshold; omitted for purely event-triggered tasks
Consumables, tooling, testing procedures

Task types (catalogue)

Removal/installation · Lubrication/Servicing · Operational test · Visual Check · Functional test · Inspection · Restoration · Discard · Software update.

Technical areas to cover

Structures · UA flight control systems · Landing gear · On-board equipment · Electrical/electronic · Propulsion · Navigation · Command/control/communication (incl. ground control system).

Evidence / Verification

Designer keeps recorded evidence of compliance.
Compliance form (provision of this MoC) compiled and signed by designer, supplied to operators applying for operational authorisation.
Operator may add tasks but must not impair effectiveness of designer-set requirements.

Assumptions & Limitations

Procedural/training provisions of OSO#03 are not addressed here — operator's responsibility.
Pre-/post-flight inspections are out of scope (covered by OSO#08).
Designers of separate kits (e.g. parachutes used as M2 mitigation) may also use this MoC for their own ICA.
Recurrent malfunctions / design-related occurrences and associated risk methodologies — see OSO#01.

References

Annex E to AMC1 to Article 11 of Regulation (EU) 2019/947
Light-UAS.2625 (SC Light UAS)

MoC Index
OSO-05 — System Safety and Reliability — design errors / FMEA
OSO-24 — Environmental Conditions — environmental qualification feeds into life limits

Open Questions

Operator-side procedural and training portion of OSO#03 not documented in this corpus.