Flight testing of RAT on 320

[nnc0]

The DGAC is to be issuing a CN (AD) shortly restricting A320 airspeed in a flight test with RAT deployed to 250 kt max. Any faster than that and it seems that the blades will only last about 2 minutes before disintegrating.

What I'm curious about though is why they don't also apply the restriction for an actual emergency deployment. ie max airspeed = 250 kt.

Anybody have any ideas on why?

[SIDSTAR]

Interesting. I'd bet they will soon.

How about the vastly increased landing distances in FCOM/QRH amendment 39 for all non-norrmal landings - eg with flaps problem. Seems like they just got the original figures wrong. Some distance factors have jumped up to 2.4 times the normal landing distance. Does anyone have any info on this?

[Genghis the Engineer]

I've no involvement with the programme, but I'd guess it may be that you term "desintegrating" maybe a little OTT. It could well be that the blades/RAT distort or damage above 320kn so that they can't be re-used? Frankly not a consideration in a real deployment, but something that you can really live without in training or routine air-testing.

As I said, pure guesswork, but it would be reasonably consistent with normal airworthiness (structural certification) practice.

G

[Down Three Greens]

Gents

I would not like to paste sections of the AD on such a public domain but I will mention that the AD was produced after RAT vibration and noise during an Airbus flight test. The AD states that in a high speed configuration the situation could lead to rupture of the blades. It is a precautionary measure.

DTG

[nnc0]

Thanks gents.

Enquiries at Airbus yielded that some airworthiness authorities require mere than just ground rig testing and that they require periodic In Flight testing of the RAT which can lead to fatigue, and I suppose distortion.

Thanks again.