Case studies
Instrumenting a production trainer without freezing the configuration
A European airframer needed instrumentation that could ship with every aircraft and still differ from one customer to the next. The answer was not a bigger unit — it was one that could be assembled differently.
The context
- Sector
- Airframer, Europe
- Platform
- Training aircraft, in production
- Scope
- Series instrumentation, line-replaceable unit
- In service
- 2024
A well-established trainer was being modernised on its existing type certificate: upgraded design, upgraded systems, same aircraft family. The instrumentation was not there for a test campaign — it was to become part of the delivered aircraft, built on the production line and supported for the life of the fleet.
The constraint: one configuration per end customer
Training aircraft are sold to operators with different requirements, and each of them specifies a different aircraft standard. The instrumentation therefore could not be a fixed article. It had to be the same equipment across every standard, configured differently, without a new qualification each time and without a wiring change on the aircraft.
That is a production requirement rather than a measurement one, and it rules out most of the field. A purpose-built unit sized for one configuration is cheaper on the first aircraft and impossible on the fourth customer.
The architecture
One unit per aircraft, built from a single stackable module set: between six and twelve acquisition modules depending on the standard, all inside the same chassis, with the data handed to an airborne computer in IRIG 106 Chapter 10 through the unit controller.
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The consequence for the airframer is that a new customer standard is an assembly decision, taken in production, not an engineering project. And because the unit is line-replaceable, an operator can swap it without an instrumentation specialist on site.
The channels
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| Channel type | Count |
|---|---|
| Discretes | 8 |
| RS-422 serial | 2 |
| Audio and HD video | 2 |
| ARINC 429 | 4 |
| Ethernet | 2 |
A modest count by flight-test standards, and deliberately so: this is an operational fit, sized for what the aircraft needs to record every day rather than for an envelope-expansion campaign.
What it changed
The flexibility that mattered was not in the specification but in the supply chain: one part number to stock, one qualification file to maintain, and a configuration decided at assembly. On a production programme that is worth more than any single technical characteristic.
What we take from it
The requirement that decided this fit was never written as a measurement requirement. It was written as "we do not know what the next customer will ask for". That is a common shape, and it is worth recognising early, because it points at a modular architecture long before anybody has counted channels.