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Forum: Rotorheads

11th Nov 2017, 00:20

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

AnFI, Sorry for the tardy response. ...

AnFI,

Sorry for the tardy response.

The answer to your first question is that for single path flight critical systems/components, an example of the FAA threshold for catastrophic failure...

Forum: Rotorheads

8th Nov 2017, 06:24

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

Unfortunately, the type of testing you describe...

Unfortunately, the type of testing you describe would not likely be helpful. What most people, including many engineers, don't understand is the fundamental purpose for conducting tests. In the...

Forum: Rotorheads

29th Oct 2017, 04:47

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

AnFI, I did not read that the planet gear...

AnFI,

I did not read that the planet gear spherical roller bearings from the two suppliers actually had different "conformal curvatures" (or osculation ratios). What I recall was that they had...

Forum: Rotorheads

25th Oct 2017, 07:22

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

gasax, Your concern about AH not yet having...

gasax,

Your concern about AH not yet having established the root cause of this problem is valid. Unfortunately, it can be extremely difficult or even impossible to diagnose such problems with 100%...

Forum: Rotorheads

29th Jul 2017, 01:41

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

Predicting propagation of a fracture within a...

Predicting propagation of a fracture within a metal structure is a fairly complicated task, mostly due to the wide range of variables involved. The fracture propagation analysis is intended to...

Forum: Rotorheads

27th Jul 2017, 02:37

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

Geoffers - The planet gears in question were made...

Geoffers - The planet gears in question were made from 16NCD13 double vacuum melt steel (AMS 6263) which is very high quality. You can find some data on the alloy here...

Forum: Rotorheads

23rd Jul 2017, 06:31

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

In the US, most newer rotorcraft gearboxes use a...

In the US, most newer rotorcraft gearboxes use a dedicated transmission oil like DOD-PRF-85734 or a commercial equivalent, rather than turbine engine oils like MIL-PRF-7808. DOD-PRF-85734...

Forum: Rotorheads

11th Jul 2017, 05:59

Replies: 212

225 cleared to fly in UK & Norway

Views: 116,959

Posted By riff_raff

You make a somewhat relevant point here. Except I...

You make a somewhat relevant point here. Except I would compare this EC225 helicopter problem to that experienced with the horizontal tail surface actuator jack screws on some MD-80 commercial...

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