buzz66-

I can't think of any other MRGB that uses the epicyclic stage ring gear as a structural member. But the AH MRGB designs are different in how they use struts to transfer rotor loads to the airframe.

However, almost every MRGB I can think of has the outer race of the epicyclic stage planet gear bearings integral to the gear. Including Bell, Boeing, AW, and EC designs.

rung gear
 

@riff raff:

If I remember well, at least CH47 (!) uses the epicyclic stage ring gear as a structural member.

But I agree with you that almost every MRGB has outer race of the epicyclic stage planet gear bearings integral to the gear.

http://icas.org/ICAS_ARCHIVE/ICAS2006/PAPERS/048.PDF

http://williams.best.vwh.net/172RG_POH/7-28.jpg

I remember from training back in the 70's that wet lines into cockpits was to be avoided at all costs as the effect of a leak was quite dramatic. We've all seen the films with the WW2 pilot getting covered in hot oil.

The quoted 210 has a working pressure of between 1000/1500 psi, modern systems have 3000 psi plus. Nobody wants that in the cockpit.

Ask any Chinook Pilot about Hydraulic Leaks in the Flight Control Closet on the Port Side of the Cockpit Companion way! Fight controls at 3000 PSI and Utility System pressure lines at 2500 PSI...makes for an interesting time.

Likewise...the Forward Transmission Oil Filter blowing off and the Sound Proofing not being installed under the Tranny gets interesting in the Cockpit as well.

What is more impressive is a fuel leak back aft when one of the 400 PSI lines with a diameter of about six inches lets go....(at least that is what One would think when a Jet Fuel Niagara Falls happens).

My new Toyota has Electric Power Steering (EPS), no pump, no fluid. Many large airplane use electric motors for landing gear and flaps (B-29).

Eurocopter / airbus helicopters use renualt and citroen parts.. there electrics suck ass...

Suck ass....
Such as their English?

SLB (Renault driver)

Gentlemen, we appear to be drifting with the tide and away from the thread's topic. (My Mini Cooper S had electric power assisted steering, sadly the wife got tired of one of the finest driving cars I ever owned ... :().


The hydraulics weren't what was wrong with the accident aircraft 225's, were they?

@Lonewolfe_50: Then let’s return to auto-transmisson gearboxes of cars. You will never find an epicyclic module with planet gearwheels being the outer race of it’s roller bearing and with a ring gear being the housing of the gearbox. By AVIO AERO resp.in H225, AS332L2 and TP400D6 this might be a standard:ugh:
(https://www.yumpu.com/xx/document/vi...0976/planetary)
https://www.yumpu.com/xx/document/vi...0976/planetary

Maybe related, or not:

Singapore delays $1 billion military helicopter buy after Super Puma crash: sources



Singapore delays $1 billion military helicopter buy after Super Puma crash: sources | Reuters

Not sure why, since the topic of this thread is actually helicopters. Cars only function in two dimensions unless one is stunt driving for a movie. Their altitude design spec is 0 feet AGL.


@ecuerilx: that's a signal sent. (Can one blame the buyer in this case for getting cold feet until a "we know why" and "here's how that's resolved" is on the table?)

@Lonewolf_50: Can you show me any gearbox which is not burdened by three dimensional forces and loads and which does know in which altitude it is running, flying or swimming?
:=

urgent questions:
 

• Where are the markets for all those H225 / AS 332L2 that are returned by the lessees - such as by CHS due to Chapter 11 petitions - to the lessors?

• What will happen with those H225 / AS332L2 which are returned by operators to the lessors because those helicopters do not meet the contractual characteristics for safe flight operations?

• How are realized alternative and just in time solutions (eg. S 92, AW 189, AW101) by industry and lessors, otherwise the lessors risk to be liable for the losses of lessees?

• How will the lessors act against AHB?

Looking on the worlds markets, these questions must be put 100 to 150 times!
Or what is the opinion of the PPRuNe Community to the situation and to the figures?

That image you linked shows an epicyclic ring gear attached by a flexure. The flexure flange is clamped between the housing faces, but is not a structural member of the housing. This flexure attachment is commonly used with large epicyclic ring gears since it provides some misalignment capability between the planet and sun gears.

As descanio noted, the CH-47 gearbox does use the epicyclic ring gear as part of the housing structure.

As for automatic auto transmissions with epicyclic gear stages, most of the ones I have seen incorporate the outer bearing race of the planet gears as part of the gear.

http://www.nsk.com/company/pressloun...s/1030/a02.jpg

@riff_raff: The Image (https://www.yumpu.com/xx/document/vi...0976/planetary) shows the TP400 main propeller gearbox on display at Paris Air Show 2013 (https://upload.wikimedia.org/wikiped...er_Gearbox.jpg).

You are very right, the flexure flange as a unit with the ring gear is clamped between the front cover and the housing by means of through-bolts and is supported or propped up directly as a fitting element (Surface pressure) in the housing.

In my view this design transfers all radial forces by the ring gear (e.g. deformation or crack of ring gear due to mashing or squelching of satellite epicyclic (broken pinion gears) directly to the housing of the PGB.

Therefore I don’t see much mechanical difference to the CH-47 and also not to the H225/AS 332 Design, where the ring gear is one part with the housing structure. Of course the construction of the TP400-D6 PGB by AVIO AERO is much friendlier to overhaul and repair.

• In a BMW or a Mercedes you will never find an auto-gearbox where the large epicyclic ring gears are parts of the housing or are in direct mechanical contact to the housing (see http://www.ipsen-blog.de/wp-content/...kgetriebe2.jpg & http://i.auto-bild.de/ir_img/1/1/6/0...d4701683b0.jpg)

• In case of gear mashing the gear housing never will explode and the cardan shaft wouldn't do the very same as the main rotor of H225LP LN-OJF did in Bergen Crash.

• In (Super) PUMA MRGB the ring gear is part of the housing!

• To incorporate the outer bearing race of the planet gear as part of the gear might be a cheap solution in automotive transmissions, but we are talking about gearboxes in aviations. High quality outer bearing races by press-in conection to the planet gears don’t make much difference in costs, but are an enormous profit in safety and reliability.

Those are precisely the four crucial core issues which were not catched by the very loud ‘engineer’ Lonewolf_50, because he lapsed up to now into a suspicious silence!

In summary: The MRGB of (Super) Puma does not even meet the present standards of automotive engineering.

Points 1 and 3 are the same point worded differently.

An automatic gearbox works by allowing the ring gear to rotate in some ratios and fixing it in others whereas the helicopter gearbox has one ratio only. Apples vs oranges.

@PhilJ: From the perspective of @lonewolf_50 you're right.

@AW009 Nothing suspicious about lack of further comment, when dealing with someone in broadcast mode who has demonstrated having an ax to grind.