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Helicopter down outside Leicester City Football Club

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Helicopter down outside Leicester City Football Club

Old 18th Dec 2018, 17:26
  #1161 (permalink)  
 
Join Date: Jan 2013
Location: Midlands
Posts: 127
Originally Posted by sycamore View Post
Pozi,I`ll try to clarify a bit,p56 #1117; if you undo the nut at the `spider end`,and the gearbox back-plate,you`should be able to remove the hyd. unit complete,leaving the t/r supported on the rotor mast,which has internal splines at it`s `top-end #1102.The spider/slider have splines matching the mast-splines,but it is difficult to determine if there is a lock-nut at the end of the rotor mast as well.The pitch control rod must run through the piston to the feedback link,and the piston limits it`s travel at each end of the jack...That`s how I see it,unless anyone can produce a full `cutaway drawing.
Thank you, you seem to be agreeing with me!
A sectional drawing of this particular unit would indeed be helpful, some of the examples posted have been "schematic" and don't show the arrangement of the control shaft and outer (hollow) shaft.

Understand how the TR will stay where it is, supported by its own bearings. But wouldn't removing and replacing the hydraulic unit be complicated by the fit of the duplex bearing? However, this isn't really relevant to the incident.
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Old 18th Dec 2018, 19:21
  #1162 (permalink)  
 
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Originally Posted by Pozidrive View Post
Understand how the TR will stay where it is, supported by its own bearings. But wouldn't removing and replacing the hydraulic unit be complicated by the fit of the duplex bearing? However, this isn't really relevant to the incident.
No. Six nuts hold the actuator (servo, hyd unit) onto the gearbox. Thereís the two nuts either end of the pitch control rod (shaft) and one bolt/ nut attaching the flying controls to the input/ feedback lever. 4 hydraulic pipe unions, and some electrical plugs. Thatís it. Very straight forward.
The pitch control rod (shaft) just passes through the centre of the duplex bearing (which is part of the spider) when the actuator (servo, hyd unit) is fitted to the back of the gearbox.

Last edited by nodrama; 18th Dec 2018 at 21:19.
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Old 18th Dec 2018, 19:42
  #1163 (permalink)  
 
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What percentage on the #1 Hydro system will auto-close the TRSOV after fluid loss/leakage?
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Old 18th Dec 2018, 19:43
  #1164 (permalink)  
 
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Originally Posted by sycamore View Post
The spider/slider have splines matching the mast-splines, but it is difficult to determine if there is a lock-nut at the end of the rotor mast as well.
The spider slider isnít splined on this aircraft type. The scissor links transfer the rotation of the tail rotor hub to the spider.
Yes, there is a Ďnutí holding the tail rotor hub on (there is always a Ďnutí), though it doesnít look like a nut in the conventional sense.
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Old 18th Dec 2018, 19:59
  #1165 (permalink)  
 
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Originally Posted by Sir Korsky View Post
What percentage on the #1 Hydro system will auto-close the TRSOV after fluid loss/leakage?
55% reservoir quantity
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Old 18th Dec 2018, 20:55
  #1166 (permalink)  
 
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Originally Posted by nodrama View Post


No. Six nuts hold the actuator (servo, hyd unit) onto the gearbox. Thereís the two nuts either end of the pitch control rod (shaft) and one bolt/ nut attaching the flying controls to the input/ feedback lever. 4 hydraulic pipe unions, a some electrical plugs. Thatís it. Very straight forward.
The pitch control rod (shaft) just passes through the centre of the duplex bearing (which is part of the spider) when the actuator (servo, hyd unit) is fitted to the back of the gearbox.
Perfectly explained. So the control shaft is an easy sliding fit through the inner race of the duplex bearing? And it's the castellated nut (and spacer) that clamp the inner race to the step at the outer end of the control shaft?

Only question left is the detail of the control shaft/outer shaft/hydraulic piston, which isn't really relevant.
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Old 18th Dec 2018, 21:12
  #1167 (permalink)  
 
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Originally Posted by Pozidrive View Post
So the control shaft is an easy sliding fit through the inner race of the duplex bearing? And it's the castellated nut (and spacer) that clamp the inner race to the step at the outer end of the control shaft?
.
Yes.
I canít help you with a detailed diagram of the servo actuator system. Iím not involved with component strip and overhaul.
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Old 18th Dec 2018, 21:23
  #1168 (permalink)  
 
Join Date: Dec 2018
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Originally Posted by nodrama View Post


No. Six nuts hold the actuator (servo, hyd unit) onto the gearbox. Thereís the two nuts either end of the pitch control rod (shaft) and one bolt/ nut attaching the flying controls to the input/ feedback lever. 4 hydraulic pipe unions, and some electrical plugs. Thatís it. Very straight forward.
The pitch control rod (shaft) just passes through the centre of the duplex bearing (which is part of the spider) when the actuator (servo, hyd unit) is fitted to the back of the gearbox.

I appreciate your contribution, however there is something in your delivery that sets the weemonkey "hang on" alarm going...
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Old 18th Dec 2018, 21:27
  #1169 (permalink)  
 
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Originally Posted by nodrama View Post


No. Six nuts hold the actuator (servo, hyd unit) onto the gearbox. Thereís the two nuts either end of the pitch control rod (shaft) and one bolt/ nut attaching the flying controls to the input/ feedback lever. 4 hydraulic pipe unions, and some electrical plugs. Thatís it. Very straight forward.
The pitch control rod (shaft) just passes through the centre of the duplex bearing (which is part of the spider) when the actuator (servo, hyd unit) is fitted to the back of the gearbox.
Part of the above is incorrect (I was watching the football, pathetic penalty shoot-out). The nut on the servo end of the pitch control rod doesnít get touched during an actuator replacement. It is part of the hyd actuator component and assembled/ locked at manufacture of the component.
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Old 18th Dec 2018, 21:44
  #1170 (permalink)  
 
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Originally Posted by nodrama View Post


55% reservoir quantity
Thanks ND - also, do you know if hot fluid is the only time an EP permits closing the main 1(2) SOV ?
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Old 19th Dec 2018, 07:55
  #1171 (permalink)  
 
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Originally Posted by Sir Korsky View Post
Thanks ND - also, do you know if hot fluid is the only time an EP permits closing the main 1(2) SOV ?
OPC ? 🙂

EP instructs main SOV closure for high fluid temperature and low fluid quantity (providing other system is serviceable)
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Old 19th Dec 2018, 12:34
  #1172 (permalink)  
 
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Originally Posted by nodrama View Post


Part of the above is incorrect (I was watching the football, pathetic penalty shoot-out). The nut on the servo end of the pitch control rod doesnít get touched during an actuator replacement. It is part of the hyd actuator component and assembled/ locked at manufacture of the component.
Yes, understood. That bit is clearly shown in the bulletin Figures.

In spite of the football, it was still a good explanation!
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Old 19th Dec 2018, 16:16
  #1173 (permalink)  
 
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Originally Posted by nodrama View Post


OPC ? 🙂

Not quite, but thanks again for your answer. I'm just interested in evolution/progression of Augusta design logic.
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