Originally Posted by
Stickshift3000
That is a very large error in CG as a result and pushes the sample in the POH way behind the aft limit. I wonder which moment arm BRM used when they determined CG for their flight tests.
There is no Type Certificate Data Sheet with moment arms which I'd use when doing weight and balance for a certified aircraft. If not certified I would check measure stuff like that myself. POHs can have typos.
The Super Decathlon's AFM had an error in crew moment arm from 1995 until a SL in 2018. That error also pushes the real CG further aft - just the rear seat moment arm and the change is about half that of the Bristell. CASA's role in that is interesting too but a topic for another thread maybe.
I have seen most of the spin testing which they’ve done and I am satisfied. It seems like more of a documentarian problem that CASA are concerned with particularly as it relates to the diferent models long wing vs short wing vs tail dragger etc. ...
I haven't seen any substantial issue raised by CASA.
Originally Posted by
mcoates
The ASTM documents list exactly what is required and this manufacture cannot prove compliance.
You need 1800 spins for basic spin compliance, and 600 more to be spin certified.
If that is the case then why doesn't CASA state that? Because it is not true?
Originally Posted by
djpil
The ASTM LSA guidance material that I have seen refers to the FAR 23 Flight Test Guide so the applicable nominal spin matrix is this one. Cross out the items not applicable. AC 23-8C has some associated notes which are relevant.
The Cessna Skycatcher saga is informative here. To that matrix I provided one would add build-up tests rather than jump into the deep end. If an external spin chute was fitted then repeat the tests without the spin chute - be cautious and build up to it again. That certainly expands the test program. Of course, as Cessna found out, if there are problems then the test program will blow out further. There is a lot of detail here:
http://flighttestsafety.org/images/s...in_Testing.ppt
If a company has already been through a development spin test program and an authority wants to see a report to show compliance then it may only get the data required to show compliance. It would be interesting to look at the CT-4 spin test report that CASA wanted for their certification of the civil registered aircraft going to Tamworth many years ago. The original spin test report was not available. The company test pilot had spun every aircraft off the production line over many years. ARDU had done comprehensive spinning tests for the first RAAF aircraft. How does the scope of that CT-4 report for CASA (for intentional spinning) compare with the Bristell report (not for intentional spinning)? CASA also has a copy of the Pitts S-2A spin test report that they may care to look at too (back then they wanted all the data, now they accept FAA certification so they haven't seen the reports for later models) - it has far fewer test points than the Bristell and it includes inverted spins too.