Custom aviation MRO software development
Maintenance software in aviation isn't about ticking off tasks, but about producing evidence: that an Airworthiness Directive was carried out within its compliance time on this serial number, that a component still has service life remaining, and that the release was signed by authorised certifying staff. Appfront builds custom software around that problem, more often as a complement to the existing M&E system than as a replacement for it.
What this page covers, and for whom
This page is about the maintenance side. You work at a Part-145-approved maintenance organisation, at a CAMO or in the technical department of an operator, and deal daily with task cards, component counters and release documents. If you are looking for something broader, such as flight tracking, crew planning or ground handling, our page on building an aviation app will serve you better.
In Europe, responsibility is divided between two roles; software that does not recognise that distinction runs into trouble. A Part-145 organisation carries out the maintenance and releases the aircraft with a certificate of release to service. A CAMO, governed since Part-CAMO in Annex Vc to Regulation (EU) No 1321/2014, determines what must be done and when: managing the aircraft maintenance programme, assessing Airworthiness Directives and Service Bulletins, keeping the records in order and carrying out the airworthiness review.
Many companies hold both approvals, but they remain two files with two manuals. In the Netherlands, the Human Environment and Transport Inspectorate issues them and supervises them.
The operational side
Work orders, task cards, the authorisations of certifying staff and the release to service itself. This is where the evidence is created that has to be produced during an audit.
The managing side
The maintenance programme, the AD status per registration and per serial number, the component counters and the records you need to be able to show for years. This is where the audit risk lies.
The space in between
The M&E system holds the planning, the stores hold the inventory, the technical log holds the flight hours and the engineer holds the reality. If those four don't talk to each other, you end up with a spreadsheet.
Component tracking is a different problem from a maintenance schedule
A maintenance schedule is tied to the aircraft: it flies, hours and cycles accumulate, and tasks fall due. Component tracking works differently. Every serial-numbered component carries its own counters, which don't move in step with the aircraft: time since new and cycles since new from manufacture, time since overhaul from the last shop visit, and time since installation from the moment it went onto this aircraft. Calendar time keeps running in the meantime, even while the component is sitting in stores.
It gets tricky when a component moves, because it takes its history with it and only the rate at which its counters accumulate changes. Take a unit from an aircraft that flew short sectors: many starts and landings, few flight hours per cycle. After a shop visit that same unit goes onto an aircraft flying long sectors. From that point the hours counter climbs quickly and the cycles counter slowly, and a different limit comes into view first. Anyone who derives service life from the utilisation of the current aircraft will get the sums wrong, in either direction.
With life-limited parts there is no room to get that arithmetic wrong. An LLP has a published retirement life in cycles, flight hours, calendar time or a combination of these, set by the manufacturer and approved as part of the type certificate. That differs from hard-time, where an item must be removed before a fixed maximum age, and from on-condition, where an inspection or measurement determines whether the item stays serviceable until the next check. With an LLP limit there is no room for that kind of judgement.
The administrative side comes on top of that. For life-limited and serial-controlled parts, back-to-birth traceability applies: an unbroken chain of records back to the original release document, the EASA Form 1 or the FAA Form 8130-3. If there is an unexplained gap in that history, the part must be treated as if no life remains. Under 145.A.42 you may only install components that carry the correct documentation, however new they are.
For software, this means the data model has to carry several independent counters per serial number, plus an installation history and the associated documents. Systems that model maintenance only per aircraft will not be able to add component tracking later on.
From Airworthiness Directive to signed evidence
An Airworthiness Directive is not advice. EASA issues one to correct an unsafe condition, and compliance is legally enforceable. It states the compliance time: a calendar date, a number of flight hours, a number of cycles or the next inspection, with the rule generally being that whichever occurs first applies.
When audits go wrong, it is rarely because the work wasn't done; it goes wrong in the chain in between. From the AD to the applicability assessment: does this apply to our registrations, and to which serial numbers? From there to a work order with the correct task card, and from execution to a signed release, where 145.A.50 requires that the certificate of release to service is only issued once certifying staff have verified that all the required maintenance has been correctly performed. That chain must also be traceable in reverse: an inspector cites an AD number and you lay the signed document beside it, for that serial number, with that date.
The AD as a record
As long as an AD lives as a PDF in a folder, its status is merely an opinion. As a record per serial number, it gets an applicability assessment, a planned implementation, an implementation date and a reference to the evidence document.
Recurring obligations
Some ADs are recurring: as soon as one is carried out, the next deadline arises, derived from the date, hours or cycles at that moment. Tracking this manually sooner or later lets one slip through.
The bulletin register
A Service Bulletin is in principle a recommendation, unless an AD refers to it. EASA asks type certificate holders to reserve the word mandatory for bulletins that are followed by an AD, but cannot enforce this. Therefore, also record why you are not carrying out a bulletin.
Ground time is the most expensive variable in the process
An aircraft that is unexpectedly grounded, aircraft on ground in the jargon, is the most costly state an operator can face. The pressure to end that situation shapes the behaviour of the entire maintenance organisation.
Maintenance planning is therefore rarely a matter of carrying out a task when it falls due. The question is which tasks you bring forward to include in a planned maintenance slot, and which you leave be. Bringing a task forward costs service life: you give up remaining hours, cycles or calendar time. Leaving it be may cost ground time at an inconvenient moment. That trade-off depends on the remaining margin, the scarcity of the slot, the availability of the part and the flight schedule.
A similar mechanism applies to defects during operations. Under the minimum equipment list, derived from the manufacturer's master minimum equipment list, an aircraft may continue flying with a known defect for a rectification interval, subject to conditions. This creates room to schedule the repair for a planned stop, but it is postponement with a clock ticking. The aircraft technical log is the pivot: it holds flight hours, cycles and the deferred defects, and it is where responsibility passes between flight operations and the CAMO.
Software that does not support this trade-off simply moves the problem into the planner's spreadsheet, where the decision falls outside the view of everyone else.
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Part-145 and Part-CAMO both stem from Regulation (EU) No 1321/2014 on continuing airworthiness. For Part-145 organisations, additional safety management requirements were introduced by Regulation (EU) 2021/1963, applicable from 2 December 2022. On the management side, Part-CAMO replaced the former approval under Part-M subpart G, with 24 March 2022 as the closing date; in addition, Part-CAO exists for smaller organisations. A Part-145 approval may be additionally recognised by, among others, the FAA, TCCA and ANAC, based on bilateral aviation safety agreements.
ATA Spec 2000 defines formats for exchanging maintenance and reliability data on aircraft, engines and components, with chapter 11 covering the XML format the industry uses for this; ATA iSpec 2200 does the same for maintenance documentation.
When you are better off not building custom software
This is a domain with mature, deeply established off-the-shelf packages. Systems such as AMOS, TRAX, Ramco Aviation, IFS Maintenix, Ultramain and Rusada ENVISION cover decades of regulation, aircraft types and component models that you would otherwise have to work out and maintain yourself. Building a complete MRO or M&E system from scratch makes little sense for almost any organisation, and we would advise against it.
There are three reasons for that. The functional surface is larger than it looks from the outside. Regulations keep moving, and with a package you pay someone else to keep up with that movement. And the burden of proof shifts: with self-built software you have to validate it yourself and anchor in your manual how the system safeguards your airworthiness records. That last point weighs the heaviest.
As a complement, custom software is certainly a sensible option. Most M&E systems are designed for the planner, not for someone wearing gloves on an apron without a reliable connection. A shop-floor app that shows only today's tasks, works offline and writes back to the source in a controlled way once connected often delivers more than a package migration. The same applies to integrations between systems that don't know each other.
There is one boundary we always make explicit: self-built software must not quietly become the authoritative record. If you want to shift that, it should be a deliberate decision that is recorded in your manual and that you discuss with your regulator.
- Shop-floor app on top of your existing M&E system
- Sites without a reliable network connection
- Integration between M&E, warehouse, time recording and tech log
- Planning challenge the package doesn't cover
- Customer portal for operators whose aircraft you maintain
- Reporting the package doesn't provide
- Data migration and clean-up around a package change
- A way of working that sets you apart in the market
Frequently asked questions about custom MRO software
We advise against that. Such packages cover decades of regulation, aircraft types and component models, and with a self-built system the burden of validation and justification falls entirely on you. We prefer to build the layer around it.
That depends on the role of the software. If the existing system remains the source for component counters, AD status and records, your evidence chain does not change. If the custom software takes on a role in recording itself, that should be described in your maintenance organisation exposition or continuing airworthiness management exposition.
No. DO-178C concerns software in airborne systems and equipment, meaning on board the aircraft; ground-based maintenance support falls outside its scope. Your obligations run through Part-145, Part-CAMO and your own manuals.
The code and documentation are yours, including access to the repository, environments and build pipeline. We describe the architecture and integrations so that another party can take them over.
Usually that is a firm requirement. We design such apps offline-first: tasks, documentation and forms stored locally on the device, input saved locally and synchronised when a connection is available. The design work lies in handling conflicts and in deciding which moment counts as the recording moment.
If your project also involves flight data, crew planning, ground handling or passenger processes, see our page on building an aviation app.
Related services
Building an aviation app
Broader than maintenance alone: flight data, crew planning, ground handling and passenger processes. If your question touches those domains, start with building an aviation app.
No decision made yet
If you are torn between a package change, an extension or doing nothing at all, that is a good starting point. Get in touch.
Walk through your maintenance process with someone who knows the chain
Tell us which system you use, where the spreadsheets are, and which step in the chain from AD to signed evidence takes the most work. From that, it often becomes clear within a single conversation whether custom development makes sense and where it should focus. If the conclusion is that you are better off not building anything, you will hear that too.