Last month we introduced Test Cells and the important function they play in verifying engine performance, but with so many test cells out there how do we know the data is “good”? There are OEM test facilities and 3rd party MRO shops who are also capable of testing engines. Test Cell Correlations are important because they provide evidence that the data produced from the 3rd party facility is traceable to a known “good” facility, usually an engine OEM. Let’s discuss the regulatory guideline for correlations and measurement systems.
14 CFR Part 43.2(a), Records of overhaul and rebuilding.
“It has been tested in accordance with approved standards and technical data, or in accordance with current standards and technical data acceptable to the Administrator, which have been developed and documented by the holder of the type certificate, supplemental type certificate, or a material, part, process, or appliance approval under [part 21 of this chapter.]
The standard for being tested in an approved facility known to produce accurate, repeatable data. That is shown by comparing the reference facility to a baseline facility. The baseline would be an OEM or facility correlated by the OEM, the reference facility has to be traceable to the OEM.
As we know test cells are complex and so are the sub-systems. Last week we touched on fuel flow and shaft horsepower but what are some additional systems that need to be accounted for?
Data reduction system: is a primary contributor, it takes the raw data and corrects it to standard day conditions.
Pressures: Include fuel flow and engine conditions are important and can be useful to troubleshoot and understand the performance of the facility and engine.
Engine Speed: Is the engine speed similar to the reference facility and producing the same shaft horsepower and torque? If so, you are well on your way to a successful correlation.
As we see above, there is a regulatory requirement for correlations and measurement systems validation is the reason for the test. Our in-house DER has experience as an FAA employee and consultant with guiding companies throughout the process and leading them to a successful approval from the FAA. Contact us today if you have any questions or need assistance, we will be happy to help!
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