Noise Certification Testing

STC Twenty One recently completed its first foray into Noise Certification testing following the installation of a Radome and Sensor Turret. Back in January, comprehensive flight tests were performed to ‘baseline’ the aircraft. Following modification these same tests were performed to evaluate potential changes to the aircraft handling and performance. In addition to these flights, it was necessary to measure the noise of the aircraft for regulatory compliance.  

With the assistance of Decibel Engineering and Anotoec, flight testing was performed in Granada, Spain. The logistical challenges of having the aircraft, specialists, crews, maintenance personnel and the various overflight permissions in place were not insignificant to say the least.

audio testing

Once all of the overflight permissions were granted (thanks to the persistence of the operations department), we had a very short window in which to test and with that the team sprang into life. Despite being very well prepared, after a lot of anxious waiting, we had to pull together in very short order to perform the test before the day’s end. Flight test instrumentation, ballast and fuel state confirmed as being all present and correct. Communications were established with the ground test team and with confirmation that the wind speeds were within limits, off we went.

The flying needed to be very precise requiring our height and speed over the microphones to be very consistent over a series of runs. The test pilot did an amazing job, completing 13 precise circuits in just one hour. To satisfy regulatory requirements we needed at least 6 good data points. In the end, we were able to get 11 solid data points (more than enough). This was very fortunate as the following day (our planned contingency day) it would not have been possible to test due to weather constraints. This type of flying requires a lot of concentration and excellent CRM. Thankfully, the operator of the aircraft provided a first-rate pilot who was able to work seamlessly with the test pilot.

With a comprehensive FTI setup and an excellent FTI engineer, it was possible for Anotec to quickly analyse the data and to confirm that no further testing would be necessary. This came as a great relief because we were out of time.

sound testing updated

All in all, it was great to be part of a cohesive team with a distinct camaraderie between all members, all striving for the same goal. These really are some of the best days to be in aviation!!

sun set