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-   -   Retractable Undercarriage (https://www.pprune.org/rotorheads/589233-retractable-undercarriage.html)

Fareastdriver 10th Jan 2017 09:12

Some electrical gizmo upset by the VTA.

Dave B 10th Jan 2017 12:00

It was incredible that some nut case at Bell decided to put an aircraft as heavy as the 214 ST on skids, Alan Bristow took one look at it and declared them insane. We did however have one A/C in from a third party, that had a rear skid brake as it was being pushed out of the hanger, the resultant bang could be heard throughout the building, and brought everybody down from all floors.
It was very lucky that no one was underneath at the time.

Sevarg 10th Jan 2017 18:48

Dave, was Ringo´s foot not involved hence an issue of safety boots all handlers?

albatross 10th Jan 2017 19:55

I was told by an older feller that in olden Daze, in the first year after introduction of the type, that if the 76 was a fixed wing, every one of them in the company would have been landed gear up due to gear extension problems. Don't know if that is true or not.
In the early 2000s we had a 76 that we flew with the gear pinned down for over a week while waiting for spare parts. Even flying with the draggy (if that is a real word) gear doors open we only seemed to loose about 4-5 knots with the same power settings.
Always made me wonder if a fixed gear with fairings would not have been just as efficient, but not as pretty, .also a considerable weight saving by getting rid of all that gear extending/retracting hardware plus a much simpler hydraulic system. I assume I am being simplistic.
Please understand I have a "bit of time" in the 76 and think it is a fine aircraft. Never had a gear problem with it.

Dave B 10th Jan 2017 22:46

Sevarg
Yes I can confirm that Ringos foot was injured in that accident,for which I felt guilty, as I had asked him to help us get the thing out of the hanger, just as he was on his way home. It was not serious thankfully and he was soon back enjoying a pint.

John Eacott 10th Jan 2017 22:54

albatross, conversely we always used the S76 gear down as 'airbrakes' on ILS approaching the MM. It was guaranteed to wipe 10-15kias off the speed and bring us back nicely onto spec; we kept 140 up until then as for Essendon 26 we often had Tullamarine jet traffic bemoaning a helicopter being 'in their way'. Bomber Brown put one 727 driver back in his box when he established that the S76 was doing 145 and the 727 a mighty 135 ;)

megan 10th Jan 2017 23:43

Only troubles I recall with the 76 was occasionally we had trouble getting the gear to lock up, which a few recycles usually fixed. Problem was proximity switches needing attention. Had one interesting one where the nose gear refused to extend on reaching home. Had a pile of sandbags put down and landed with the nose resting on same. Oleo had not extended on the previous take off and scissor link jammed up against the actuator.

John R81 11th Jan 2017 10:19

On the smaller side (OP question) there was the Augusta A109A II which failed to extend its landing gear at Redhill, with David Cameron on board.


Press "sensational" report
and AAIB report; the handle came off which eliminated both the main system and the back-up system.

ShyTorque 11th Jan 2017 12:20


Originally Posted by John Eacott (Post 9636703)
albatross, conversely we always used the S76 gear down as 'airbrakes' on ILS approaching the MM. It was guaranteed to wipe 10-15kias off the speed and bring us back nicely onto spec; we kept 140 up until then as for Essendon 26 we often had Tullamarine jet traffic bemoaning a helicopter being 'in their way'. Bomber Brown put one 727 driver back in his box when he established that the S76 was doing 145 and the 727 a mighty 135 ;)

I have occasionally been directed to "make best airspeed" in the A109 when being vectored in for an ILS, to fit in with the jet fixed wing pattern. 165kts on final approach is often enough to prompt ATC to ask me to slow down a bit because I'm catching up the preceding airliner. One has to do these things to show them we rotary folk can be very flexible. ;-)

212man 11th Jan 2017 13:04


Originally Posted by John Eacott (Post 9636703)
albatross, conversely we always used the S76 gear down as 'airbrakes' on ILS approaching the MM. It was guaranteed to wipe 10-15kias off the speed and bring us back nicely onto spec; we kept 140 up until then as for Essendon 26 we often had Tullamarine jet traffic bemoaning a helicopter being 'in their way'. Bomber Brown put one 727 driver back in his box when he established that the S76 was doing 145 and the 727 a mighty 135 ;)

But not lowering the gear above 130 kias I assume......

oldbeefer 11th Jan 2017 13:11

The added complexity of the hyd system can be a problem. In the early days of the Puma in the RAF I lowered the gear at the end of a night sortie. The pressure in the nose jack blew the end off leaving me with only the two mains down. Raising the emergency gear lever stopped the remaining hyd fluid dumping, so at least I got the AP back. Oh, and I was low on fuel, so had to do a refuel in the hover while sandbags were obtained to build a mound for the nose area during landing.

ShyTorque 11th Jan 2017 13:44

Oldbeefer, and if the nose leg "down" hose blows, even the "emergency reserve" of hydraulic fluid goes through the same hole....as I found out in Belize. The cavitating hydraulic pump makes a very frightening noise, too.... :-(

Fareastdriver 11th Jan 2017 18:19

The Puma, and subsequent descendants, had a restrictor valve inserted in the nose jack at the down hydraulic entry to slow the lowering and avoiding it slamming against the internal stops. I had it happen once but I didn't worry about it after I had isolated the hydraulics. On landing the nosewheel is jammed against the bay wall and the debris from the fractured jack prevents it from moving back so sandbags are unnecessary.

This was in the Thetford PTA and it was a toss up as to whether to fly it back to Odiham as both hydraulic tanks were still full. In the end we changed the nosewheel jack on site.

CRAN 12th Jan 2017 22:11

One additional question guys:

How does the parking brake typically function? Is it controlled solely at the pilots discretion or does it automatically release or come on when the gear is lowered?

Cheers,
CRAN

John Eacott 12th Jan 2017 23:45


Originally Posted by CRAN (Post 9639048)
One additional question guys:

How does the parking brake typically function? Is it controlled solely at the pilots discretion or does it automatically release or come on when the gear is lowered?

Cheers,
CRAN

At pilots discretion in all that I've operated: I can't think of any reason for it to be automatically applied!

Some aircraft use auxiliary hydraulic pressure for the parking brake, which will bleed off and thus render the parking brake useless for the next start. Tedious as you should then chock the mainwheels when leaving the machine and especially before the next start to secure the aircraft. You then have to remove the chocks before taxi which can require groundcrew to remove and (possibly) stow them back in the boot of the helicopter before you taxi off on your merry way.

Ascend Charlie 13th Jan 2017 02:08

It functions by the pilot (usually) pulling out the park brake handle and pressing the footbrakes hard, then (sometimes) turning the park brake handle - before start, so he can then put the chox in the boot.

To release, usually just press the footbrakes (handle pops in) or press the brakes and turn the park brake handle.

It is possible to get airborne from a hover and forget to release the park brake, which then comes as a rude surprise when you do your next running (screech!) landing.

ShyTorque 13th Jan 2017 06:57

On the A109 series pulling a T handle applies the parking brakes on the main wheels via the utilities hydraulic system, so no need to apply pressure to the toe brakes. Turning the same handle locks them on. But the pressure dissipates after an indeterminate time after shutdown so the aircraft needs to be chocked.

CRAN 13th Jan 2017 09:40

Thanks for the replies guys, most useful.

With regards the toes brakes, do they brake each rear wheel independently as they do on tractors so that you can readily do spots turns? I presume this is the case...

Many thanks,
CRAN

212man 13th Jan 2017 09:51


Originally Posted by CRAN (Post 9639389)
Thanks for the replies guys, most useful.

With regards the toes brakes, do they brake each rear wheel independently as they do on tractors so that you can readily do spots turns? I presume this is the case...

Many thanks,
CRAN

Yes; they do.

CRAN 13th Jan 2017 09:57

Thanks 212man.

CRAN


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