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JL2A
Joined: 07 Apr 2015 Posts: 113 Location: Australia
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Posted: Sat Oct 28, 2017 4:52 pm Post subject: Gear not locking up |
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Strange problem, after a few cycles in same day the uplocks are not engaging. It seems the uplock actuators are staying extended, which prevents the hooks from snapping locked.
On ground, with gear handle in neutral the actuator pins stay out.
Solution seems to be closing main air bottle valve, draining all air out of system, the pins then retract. Then it is good for another few retraction cycles.
This is after a complete replacement of the solid and flexible air lines in the entire gear system, and 2 x diverter valves on the MLG uplocks about 2 months ago, problem only appearing after 20 hours or so.
Leak? Mis-directed line?
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Lancer
Joined: 21 Apr 2016 Posts: 30 Location: Cairns, Australia
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Posted: Tue Nov 14, 2017 3:07 am Post subject: Re: Gear not locking up |
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Is the Emergency air valve securely closed?
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dsavarese0812(at)bellsout Guest
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Posted: Tue Nov 14, 2017 4:47 am Post subject: Gear not locking up |
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CJ6 or Yak 52?
When was the last time you overhauled the uplock actuators themselves?
If the emergency air valve was leaking, it could cause the gear not to retract at all since the emergency air would be forcing the shuttle valve or diverter valve to block the main side, keeping pressure on the down side of the actuator, thus preventing the gear from retracting.
If the main system is keeping the uplock pin out, when you place the gear selector in neutral, it is suppose to depressurize the uplock actuator allowing the pin to retract. On the 52, the uplock actuator has two lines connected to it. The one in the middle of the actuator is the main system and the one to the rear is the emergency side. On the CJ, you have two diverter valves connected to a single port on the uplock actuator. One diverter valve for the main and one for the emergency.
With the main air turned off and the gear selectors in neutral front and rear and the uplock pin out, try removing the air lines one at a time from one the uplock actuators or diverter valves to see which side, main or emergency, is keeping pressure on the uplock actuator, forcing the pin to stay out. If you find there is no pressure on the actuator or diverter valve and the pin remains out, pull the uplock actuator, disassemble, clean and overhaul it because the spring inside the uplock actuator is not able to retract the pin when no pressure is on the uplock actuator.
Dennis
From: Lancer <lrob4783(at)bigpond.net.au>
To: yak-list(at)matronics.com
Sent: Tuesday, November 14, 2017 6:10 AM
Subject: Re: Gear not locking up
--> Yak-List message posted by: "Lancer" <lrob4783(at)bigpond.net.au (lrob4783(at)bigpond.net.au)>
Is the Emergency air valve securely closed?
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Dawg
Joined: 19 May 2013 Posts: 355
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Posted: Tue Nov 14, 2017 6:50 am Post subject: Gear not locking up |
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What’s your air pressure when retracting? I just went thru this? Will negative Gs lock them up?
On Nov 14, 2017, at 21:45, A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:
Quote: | CJ6 or Yak 52?
When was the last time you overhauled the uplock actuators themselves?
If the emergency air valve was leaking, it could cause the gear not to retract at all since the emergency air would be forcing the shuttle valve or diverter valve to block the main side, keeping pressure on the down side of the actuator, thus preventing the gear from retracting.
If the main system is keeping the uplock pin out, when you place the gear selector in neutral, it is suppose to depressurize the uplock actuator allowing the pin to retract. On the 52, the uplock actuator has two lines connected to it. The one in the middle of the actuator is the main system and the one to the rear is the emergency side. On the CJ, you have two diverter valves connected to a single port on the uplock actuator. One diverter valve for the main and one for the emergency.
With the main air turned off and the gear selectors in neutral front and rear and the uplock pin out, try removing the air lines one at a time from one the uplock actuators or diverter valves to see which side, main or emergency, is keeping pressure on the uplock actuator, forcing the pin to stay out. If you find there is no pressure on the actuator or diverter valve and the pin remains out, pull the uplock actuator, disassemble, clean and overhaul it because the spring inside the uplock actuator is not able to retract the pin when no pressure is on the uplock actuator.
Dennis
From: Lancer <lrob4783(at)bigpond.net.au (lrob4783(at)bigpond.net.au)>
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Tuesday, November 14, 2017 6:10 AM
Subject: Re: Gear not locking up
--> Yak-List message posted by: "Lancer" <lrob4783(at)bigpond.net.au (lrob4783(at)bigpond.net.au)>
Is the Emergency air valve securely closed?
--------
You can run but you can't hide
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=474963#474963
-= --> http://www.matronics.com/Navigator?Yak-List
great content also available via the Web Forums!
s.matronics.com/" target="_blank">http://forums.matronics..matronics.com/" target="_blank" = ="" ="" -matt="" dralle,="" list="" admin.
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dsavarese0812(at)bellsout Guest
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Posted: Tue Nov 14, 2017 7:04 am Post subject: Gear not locking up |
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I'm pretty certain he said the uplock pins won't retract. With the pins out, the parrot hooks will not lock in position, which are a mechanical locking mechanism
Dennis.
From: Bill Geipel <l129bs(at)gmail.com>
To: yak-list(at)matronics.com
Sent: Tuesday, November 14, 2017 9:53 AM
Subject: Re: Re: Gear not locking up
What’s your air pressure when retracting? I just went thru this? Will negative Gs lock them up?
On Nov 14, 2017, at 21:45, A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:
Quote: | CJ6 or Yak 52?
When was the last time you overhauled the uplock actuators themselves?
If the emergency air valve was leaking, it could cause the gear not to retract at all since the emergency air would be forcing the shuttle valve or diverter valve to block the main side, keeping pressure on the down side of the actuator, thus preventing the gear from retracting.
If the main system is keeping the uplock pin out, when you place the gear selector in neutral, it is suppose to depressurize the uplock actuator allowing the pin to retract. On the 52, the uplock actuator has two lines connected to it. The one in the middle of the actuator is the main system and the one to the rear is the emergency side. On the CJ, you have two diverter valves connected to a single port on the uplock actuator. One diverter valve for the main and one for the emergency.
With the main air turned off and the gear selectors in neutral front and rear and the uplock pin out, try removing the air lines one at a time from one the uplock actuators or diverter valves to see which side, main or emergency, is keeping pressure on the uplock actuator, forcing the pin to stay out. If you find there is no pressure on the actuator or diverter valve and the pin remains out, pull the uplock actuator, disassemble, clean and overhaul it because the spring inside the uplock actuator is not able to retract the pin when no pressure is on the uplock actuator.
Dennis
From: Lancer <lrob4783(at)bigpond.net.au (lrob4783(at)bigpond.net.au)>
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Sent: Tuesday, November 14, 2017 6:10 AM
Subject: Re: Gear not locking up
--> Yak-List message posted by: "Lancer" <lrob4783(at)bigpond.net.au (lrob4783(at)bigpond.net.au)>
Is the Emergency air valve securely closed?
--------
You can run but you can't hide
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=474963#474963
-= --> http://www.matronics.com/Navigator?Yak-List
great content also available via the Web Forums!
s.matronics.com/" target="_blank">http://forums.matronics..matronics.com/" target="_blank" = ="" ="" -matt="" dralle,="" list="" admin.
http://www.matronics.com/contribution
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wlannon(at)shaw.ca Guest
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Posted: Wed Nov 15, 2017 10:41 am Post subject: Gear not locking up |
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Hi Dennis;
As you note there are two diverter (emergency) valves for each gear on the CJ. One valve supplies either normal or emerg. air to release the uplock actuator while the other valve supplies the same air supply to the down side of the gear actuator.
Walt
From: A. Dennis Savarese (dsavarese0812(at)bellsouth.net)
Sent: Tuesday, November 14, 2017 4:45 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: Re: Gear not locking up
CJ6 or Yak 52?
When was the last time you overhauled the uplock actuators themselves?
If the emergency air valve was leaking, it could cause the gear not to retract at all since the emergency air would be forcing the shuttle valve or diverter valve to block the main side, keeping pressure on the down side of the actuator, thus preventing the gear from retracting.
If the main system is keeping the uplock pin out, when you place the gear selector in neutral, it is suppose to depressurize the uplock actuator allowing the pin to retract. On the 52, the uplock actuator has two lines connected to it. The one in the middle of the actuator is the main system and the one to the rear is the emergency side. On the CJ, you have two diverter valves connected to a single port on the uplock actuator. One diverter valve for the main and one for the emergency.
With the main air turned off and the gear selectors in neutral front and rear and the uplock pin out, try removing the air lines one at a time from one the uplock actuators or diverter valves to see which side, main or emergency, is keeping pressure on the uplock actuator, forcing the pin to stay out. If you find there is no pressure on the actuator or diverter valve and the pin remains out, pull the uplock actuator, disassemble, clean and overhaul it because the spring inside the uplock actuator is not able to retract the pin when no pressure is on the uplock actuator.
Dennis
From: Lancer <lrob4783(at)bigpond.net.au>
To: yak-list(at)matronics.com
Sent: Tuesday, November 14, 2017 6:10 AM
Subject: Re: Gear not locking up
--> Yak-List message posted by: "Lancer" <lrob4783(at)bigpond.net.au (lrob4783(at)bigpond.net.au)>
Is the Emergency air valve securely closed?
--------
You can run but you can't hide
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=474963#474963
-= --> http://www.matronics.com/Navigator?Yak-List
great content also available via the Web Forums!
s.matronics.com/" target="_blank">http://forums.matronics.com
rget=_blank Admin. Dralle, -Matt =" " list>
http://www.matronics.com/contribution
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dsavarese0812(at)bellsout Guest
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Posted: Wed Nov 15, 2017 11:57 am Post subject: Gear not locking up |
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Thanks Walt.
Dennis
A. Dennis Savarese
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 11/15/2017 1:39 PM, Walter Lannon wrote:
Quote: | Hi Dennis;
As you note there are two diverter (emergency) valves for each gear on
the CJ. One valve supplies either normal or emerg. air to release
the uplock actuator while the other valve supplies the same air supply
to the down side of the gear actuator.
Walt
*From:* A. Dennis Savarese <mailto:dsavarese0812(at)bellsouth.net>
*Sent:* Tuesday, November 14, 2017 4:45 AM
*To:* yak-list(at)matronics.com <mailto:yak-list(at)matronics.com>
*Subject:* Re: Re: Gear not locking up
CJ6 or Yak 52?
When was the last time you overhauled the uplock actuators themselves?
If the emergency air valve was leaking, it could cause the gear not to
retract at all since the emergency air would be forcing the shuttle
valve or diverter valve to block the main side, keeping pressure on
the down side of the actuator, thus preventing the gear from retracting.
If the main system is keeping the uplock pin out, when you place the
gear selector in neutral, it is suppose to depressurize the uplock
actuator allowing the pin to retract. On the 52, the uplock actuator
has two lines connected to it. The one in the middle of the actuator
is the main system and the one to the rear is the emergency side. On
the CJ, you have two diverter valves connected to a single port on the
uplock actuator. One diverter valve for the main and one for the
emergency.
With the main air turned off and the gear selectors in neutral front
and rear and the uplock pin out, try removing the air lines one at a
time from one the uplock actuators or diverter valves to see which
side, main or emergency, is keeping pressure on the uplock actuator,
forcing the pin to stay out. If you find there is no pressure on the
actuator or diverter valve and the pin remains out, pull the uplock
actuator, disassemble, clean and overhaul it because the spring inside
the uplock actuator is not able to retract the pin when no pressure is
on the uplock actuator.
Dennis
------------------------------------------------------------------------
*From:* Lancer <lrob4783(at)bigpond.net.au>
*To:* yak-list(at)matronics.com
*Sent:* Tuesday, November 14, 2017 6:10 AM
*Subject:* Re: Gear not locking up
<mailto:lrob4783(at)bigpond.net.au>>
Is the Emergency air valve securely closed?
--------
You can run but you can't hide
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=474963#474963
-= --> http://www.matronics.com/Navigator?Yak-List
great content also available via the Web Forums!
s.matronics.com/" target="_blank">http://forums.matronics.com
rget=_blank Admin. Dralle, -Matt =" " list>
http://www.matronics.com/contribution
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JL2A
Joined: 07 Apr 2015 Posts: 113 Location: Australia
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Posted: Thu Nov 23, 2017 11:49 am Post subject: Re: Gear not locking up |
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As initially suspected, problem was a slow leak in diverter valve on landing gear.
Overhauled with one of Doug's kits, all good.
One for the matronics knowledge bank.
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