ADP Run Logic on 747-400
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ADP Run Logic on 747-400
I seem to recall a previous question on this subject, but can't
seem to find it...
On some 747-400's, the ADP's are activated by "Flaps In Motion"
and "Flaps Out of UP signals" (amongst other things). What
generates these signals?
Flap Position transmitters (L/E? I/B TE? O/B TE Flap?)
Flap I/P actuator feedback?
Flap Lever RVDT's?
A combination of these?
I understand that a specific Flap Control Computer handles each
ADP and that there is no FCU redundancy for ADP control. i.e. The
Right FCU only handles the #1 ADP and the Left FCU handles
only the #4 ADP. Is this correct?
Thanks.
Regards.
Q.
seem to find it...
On some 747-400's, the ADP's are activated by "Flaps In Motion"
and "Flaps Out of UP signals" (amongst other things). What
generates these signals?
Flap Position transmitters (L/E? I/B TE? O/B TE Flap?)
Flap I/P actuator feedback?
Flap Lever RVDT's?
A combination of these?
I understand that a specific Flap Control Computer handles each
ADP and that there is no FCU redundancy for ADP control. i.e. The
Right FCU only handles the #1 ADP and the Left FCU handles
only the #4 ADP. Is this correct?
Thanks.
Regards.
Q.
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Er... thanks, ASFKAP... Now I have two questions/problems 
(My original one about flaps... and now a new one about Body Gear Steering).
I have no idea why the BG steering should trigger an ADP to run on a 747-400 (I was under the impression that with the engines stopped, selecting the ADP to AUTO would run the ADP's continuously anyway).
Cheers.
Q.
(My original one about flaps... and now a new one about Body Gear Steering).
I have no idea why the BG steering should trigger an ADP to run on a 747-400 (I was under the impression that with the engines stopped, selecting the ADP to AUTO would run the ADP's continuously anyway).
Cheers.
Q.
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Q & ASFKAP- on the Classic 747, the Nr 1 ADP kicks on at 22.5 deg nose steering angle, just in case it wasn't selected to Auto; its to drive the body gear steering which becomes active at that point.
The Reverend
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tinyrice, I don't know what kind of 747 Classic you have operated, but all the ones I have in my logbook; i.e -100,-200,-300 with various engines, P&W, RR, CF6, were all the same. ADP operation depended on switch position. In Auto, pump runs when system demand causes EDP output pressure to fall below 2,600 psi. Once started, pump will run for at least ten seconds (or as long as system demand prevails). In off position,pneumatic supply is shut off and pump will not operate. With switch in continuous posn. pump will operate continuously.
I don't know about the -400, they don't have flight engineers on them but I shouldn't think the hydraulic system would differ much from the classic.
I don't know about the -400, they don't have flight engineers on them but I shouldn't think the hydraulic system would differ much from the classic.
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The ADP's must be in Auto. The FCU R will signal Hyd Sys 1 & FCU L will signal Hyd Sys 4 through there associated HYDIM card. On GE and P & W aircraft the pumps will run continously in flight with flaps extended. On the ground they will only run until flap position matches that of flap handle. As you say there is no FCU redundancy for this feature. If either FCU L or R is inop the flightcrew would have to select ADP 1 or 4 to On manually during landing/take-off. Not sure about the RR equipped aircraft, can you help us out here Spannersatcx?
The B747-200 has none of the above and just uses EDP low presssure (2600psi) as a signal to run the ADP in Auto, it runs for 10 to 12 seconds afgter 2800psi is attained.
As for the Body Gear Steering, we tow with the ADP at Auto so would run all the time.
Hope this is of some help.
The B747-200 has none of the above and just uses EDP low presssure (2600psi) as a signal to run the ADP in Auto, it runs for 10 to 12 seconds afgter 2800psi is attained.
As for the Body Gear Steering, we tow with the ADP at Auto so would run all the time.
Hope this is of some help.
Last edited by Denzil; 1st Jun 2002 at 12:45.
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747-400 (GE) #1 and #4 ADP's will run continuously in AUTO if the FUEL CUT-OFF switch is at CUT-OFF. Otherwise they will run in AUTO if the EDP pressure drops below 1400 PSI for longer than 0.3 secs (pump will then run for 14 secs to prevent cycling of ADP). If the TE FLAPS are away from ZERO position in the AIR the ADP will also run continuously . TE FLAP activation is like DENZIL said from the FCU's.
#2 and #3 ACMP's will also run if system pressure drops to 1400 PSI or the FUEL CUT-OFF switch is at OFF.
All logic is processed by the HYDIM.
#2 and #3 ACMP's will also run if system pressure drops to 1400 PSI or the FUEL CUT-OFF switch is at OFF.
All logic is processed by the HYDIM.
Usual disclaimers apply!
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I see what you mean QAVION the AMM and the schematics are not very good so it's back to the training notes and mine state the right FCU will provide the signal to HYDIM system 1 card to turn on the pump (demand) for hyd. sys.1 whenever the flap control lever is repositioned and until the flaps are in agreement with the flap handle .The left FCU will do the same for sys 4.
So I would guess the answer to you original Q must be the flap handle RVDT
and the PFM in the FCU.
So I would guess the answer to you original Q must be the flap handle RVDT
and the PFM in the FCU.
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"The left FCU will do the same for sys 4.
So I would guess the answer to you original Q must be the flap handle RVDT and the PFM in the FCU."
Thanks (to all). It's the PFM that I'm interested in.
Is it smart enought to not run the pumps if,
say, Flaps 1 is selected (from up) ...as the leading
edges won't require hydraulics (I guess I should
now redefine my question to only include RR-
powered aircraft, which, as a rule, don't seem to
have the Flaps Out of Up logic). Is the PFM also
magic enough to know when, say, the inboard
TE's only are running out/in (say due to a
drive failure or flap transmitter failure) and will
only run the respective hydraulic system for those
flaps it can control or see the position of.
The logic is probably so complex, I doubt I would
simulate this on the ground (using a real aircraft)..
and I wonder if the accuracy of a simulator would
be able to mimic the failure of specific flap position
transmitters. If there are any RR-powered 744
pilots out there, you may be able to provide the
first piece(s) of the jigsaw puzzle.... Do the ADP's
operate when the L/E flaps are extended to
Flaps 1 in the air? (by observing the Hydraulic
synoptic during this period).
Thanks again!
Cheers.
Q.
So I would guess the answer to you original Q must be the flap handle RVDT and the PFM in the FCU."
Thanks (to all). It's the PFM that I'm interested in.
Is it smart enought to not run the pumps if,
say, Flaps 1 is selected (from up) ...as the leading
edges won't require hydraulics (I guess I should
now redefine my question to only include RR-
powered aircraft, which, as a rule, don't seem to
have the Flaps Out of Up logic). Is the PFM also
magic enough to know when, say, the inboard
TE's only are running out/in (say due to a
drive failure or flap transmitter failure) and will
only run the respective hydraulic system for those
flaps it can control or see the position of.
The logic is probably so complex, I doubt I would
simulate this on the ground (using a real aircraft)..
and I wonder if the accuracy of a simulator would
be able to mimic the failure of specific flap position
transmitters. If there are any RR-powered 744
pilots out there, you may be able to provide the
first piece(s) of the jigsaw puzzle.... Do the ADP's
operate when the L/E flaps are extended to
Flaps 1 in the air? (by observing the Hydraulic
synoptic during this period).
Thanks again!
Cheers.
Q.
Hi Q
We did this particular dance some time back.
It's a funny old logic system and gets its inputs from flap requests and EDP output pressure. The flap logic in 'Roller' powered aircraft is different to the P&Ws and GEs. The flap logic inputs are as given in the MM. The EDP failure case is always looking at the EDP output pressure and, if that drops below the stipulated cut-in pressure, the ADP will run AND CONTINUE TO RUN until the EDP pressure increases above 1600 psi. (N.B. The 12 - 14 second run parameter is disabled as long as the EDP pressure remains below 1600 psi)
When I was still active in the 400 arena, we checked this area with Boeing, including the apparent anomalies of cut-in pressures on RR as against other power plants. I posted the results here about two years or so ago but the recent Pprune software upheaval may well have consigned the archive to the great 'wheely-bin' of the ether.
I will do a search through my papers to see if I still have the original correspondence and post, if successful.
Rgds
We did this particular dance some time back.
It's a funny old logic system and gets its inputs from flap requests and EDP output pressure. The flap logic in 'Roller' powered aircraft is different to the P&Ws and GEs. The flap logic inputs are as given in the MM. The EDP failure case is always looking at the EDP output pressure and, if that drops below the stipulated cut-in pressure, the ADP will run AND CONTINUE TO RUN until the EDP pressure increases above 1600 psi. (N.B. The 12 - 14 second run parameter is disabled as long as the EDP pressure remains below 1600 psi)When I was still active in the 400 arena, we checked this area with Boeing, including the apparent anomalies of cut-in pressures on RR as against other power plants. I posted the results here about two years or so ago but the recent Pprune software upheaval may well have consigned the archive to the great 'wheely-bin' of the ether.
I will do a search through my papers to see if I still have the original correspondence and post, if successful.
Rgds
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"I will do a search through my papers to see if I still have the original correspondence and post, if successful.
Thanks, CJ.
An independent source confirmed a few days ago that the ADP's run on a CF6-powered 744 even when selecting Flap 1 (so I suspect that the logic is fairly dumb, not actually looking at the requirement for hydraulics). This may even be the case when the flaps have switched to Primary Electric ops during a hydraulic flap drive failure.
Cheers.
Q.
Thanks, CJ.
An independent source confirmed a few days ago that the ADP's run on a CF6-powered 744 even when selecting Flap 1 (so I suspect that the logic is fairly dumb, not actually looking at the requirement for hydraulics). This may even be the case when the flaps have switched to Primary Electric ops during a hydraulic flap drive failure.
Cheers.
Q.
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Flaps > 0 in flt and Flaps in transit (magenta on EICAS) on ground, will run ADP's. This is what I originally said!!!! The FCU's will still signal the ADP's to run in Primary Electric mode. as for the logic, it must be simple it's a Boeing
By the way any jobs going in Oz????
By the way any jobs going in Oz????
Last edited by Denzil; 6th Jun 2002 at 20:36.
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"Flaps > 0 in flt and Flaps in transit (magenta on EICAS) on ground, will run ADP's. This is what I originally said!!!!"
There was probably still room for abiguity, Denzil (at least in my mind ). i.e. Flaps > 0 can mean
1. Flap lever greater than zero
2. TE flap position greater than zero
3. Any flap greater than zero
4. Etc...
Yes, GE/P&W-powered 744's have both "flaps out of up logic" AND "flaps in transit logic" but, unfortunately, the "out of up" logic masks the flaps in transit logic. I'm wondering how the flaps in transit logic behaves by itself (as on the RR-powered aircraft).
"The FCU's will still signal the ADP's to run in Primary Electric mode. as for the logic, it must be simple it's a Boeing "
As a maintenance engineer, that's the way (ah hah) I like it
"By the way any jobs going in Oz????"
If there is/was, I'd say chances are that most jobs will be/have already been swallowed up by ex-Ansett personnel (after Ansett's collapse).
Cheers.
Q.
There was probably still room for abiguity, Denzil (at least in my mind
). i.e. Flaps > 0 can mean1. Flap lever greater than zero
2. TE flap position greater than zero
3. Any flap greater than zero
4. Etc...
Yes, GE/P&W-powered 744's have both "flaps out of up logic" AND "flaps in transit logic" but, unfortunately, the "out of up" logic masks the flaps in transit logic. I'm wondering how the flaps in transit logic behaves by itself (as on the RR-powered aircraft).
"The FCU's will still signal the ADP's to run in Primary Electric mode. as for the logic, it must be simple it's a Boeing "
As a maintenance engineer, that's the way (ah hah) I like it
"By the way any jobs going in Oz????"
If there is/was, I'd say chances are that most jobs will be/have already been swallowed up by ex-Ansett personnel (after Ansett's collapse).
Cheers.
Q.
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I think there is some confusion here and since I am currently studying ADP logic on 747s lets see if I can clear this up.
All 747 series aircraft carry the same Fairchild Controls ADP. The design is 35 years old, though there is a replacement that is not only more powerful, but MUCH quieter and is found on the 767 & 777.
The ADP is designed to supplement hydraulic pressure during times of low pressure, failure or when the airplane is configured such that a failure may cause an unrecoverable configuration(ie. can't get the flaps/gear up for go around.
It is different on all three engine configurations as far as where the hydraulic pressure must dip to come on automatically. The RR version comes on first and once on remains that way until cycled(this is due to the RB211 having a small core). The GE and Pratt are relatively the same.
Flap movement on ground can make the ADP come on. Anytime the Flap lever is in excess of 25 degrees the ADP is on and running continually. Excessive control input by the pilot can also make them come on. Fuel cutoff or flow failure causes them to come on sensing the impending engine failure.
Some operators OPs manual calls for the ADP to be set to ON during approach. Most set to Auto.
How you guys like the noise coming off of the ADP?
All 747 series aircraft carry the same Fairchild Controls ADP. The design is 35 years old, though there is a replacement that is not only more powerful, but MUCH quieter and is found on the 767 & 777.
The ADP is designed to supplement hydraulic pressure during times of low pressure, failure or when the airplane is configured such that a failure may cause an unrecoverable configuration(ie. can't get the flaps/gear up for go around.
It is different on all three engine configurations as far as where the hydraulic pressure must dip to come on automatically. The RR version comes on first and once on remains that way until cycled(this is due to the RB211 having a small core). The GE and Pratt are relatively the same.
Flap movement on ground can make the ADP come on. Anytime the Flap lever is in excess of 25 degrees the ADP is on and running continually. Excessive control input by the pilot can also make them come on. Fuel cutoff or flow failure causes them to come on sensing the impending engine failure.
Some operators OPs manual calls for the ADP to be set to ON during approach. Most set to Auto.
How you guys like the noise coming off of the ADP?
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What I am reading in the Boeing Maintenance Manual (my bible) contradicts a lot of the answers that are being provided here (and by my other, normally reliable source).
The testing of the 747-400 1 and 4 ADP's involves, in one part, the selection of Flaps 5. This seems to suggest that Flaps 1 is insufficient to activate the ADP (It also repeatedly mentions trailing edge flap being greater than 0, not leading edges greater than 0). I don't think the aircraft logic is a dumb as being made out here. Perhaps the confusion is arising from the fact that there are a number of time delays built into the system. If you are retracting flaps after landing to UP, with the engines still running, then the ADP's should run for a minimum of 10 seconds after the TE have stopped moving (talking here about the flaps in motion logic). So the ADP's will still be running with the TE flaps up and probably after the LE flaps have retracted also.
If someone could confirm, on departure (after pushback/on the ground), with the engines running on a RR, GE or P&W -powered 747-400 that the selection of Flaps 1 only (no further) from UP, will not activate the ADP's, I would be most appreciative.
If the Boeing Maintenance Manual is wrong, as it sometimes is (just as pilots' manuals are), then I will gladly let Boeing know.
Thanks.
Regards.
Q.
The testing of the 747-400 1 and 4 ADP's involves, in one part, the selection of Flaps 5. This seems to suggest that Flaps 1 is insufficient to activate the ADP (It also repeatedly mentions trailing edge flap being greater than 0, not leading edges greater than 0). I don't think the aircraft logic is a dumb as being made out here. Perhaps the confusion is arising from the fact that there are a number of time delays built into the system. If you are retracting flaps after landing to UP, with the engines still running, then the ADP's should run for a minimum of 10 seconds after the TE have stopped moving (talking here about the flaps in motion logic). So the ADP's will still be running with the TE flaps up and probably after the LE flaps have retracted also.
If someone could confirm, on departure (after pushback/on the ground), with the engines running on a RR, GE or P&W -powered 747-400 that the selection of Flaps 1 only (no further) from UP, will not activate the ADP's, I would be most appreciative.
If the Boeing Maintenance Manual is wrong, as it sometimes is (just as pilots' manuals are), then I will gladly let Boeing know.
Thanks.
Regards.
Q.
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From Doc 29-11-08......"When engine driven hydraulic pressure falls below 2600 +/-50 psig or the aircraft flaps are set to greater than approximately 25 degrees, the turbine(ADP) assemblies will automatically start up to provide additional hydraulic pressure."
Now we do have a noise issue during taxi at some major EU airports caused by the ADP. Depending on what the piltos are doing the Hydraulics can get taxed during taxi to Takeoff and the ADPs come on. At idle all the way up to approach power the ADPs are louder than the engines themselves. This happens more often on RR powered airplanes than the GE or the Pratt. Also the RR configuration is different than the GE or the Pratt such that it allows more noise to escape out the boat tail.
From what the hydraulics guys are telling me, flushing a toilet can cause the ADPs to come on.
Oh, there are two configurations on ADP and are operator specified.... The operator can specify 2 per wing or 2 per airplane. Have no info on which configuration is more prominent out there.
Now we do have a noise issue during taxi at some major EU airports caused by the ADP. Depending on what the piltos are doing the Hydraulics can get taxed during taxi to Takeoff and the ADPs come on. At idle all the way up to approach power the ADPs are louder than the engines themselves. This happens more often on RR powered airplanes than the GE or the Pratt. Also the RR configuration is different than the GE or the Pratt such that it allows more noise to escape out the boat tail.
From what the hydraulics guys are telling me, flushing a toilet can cause the ADPs to come on.
Oh, there are two configurations on ADP and are operator specified.... The operator can specify 2 per wing or 2 per airplane. Have no info on which configuration is more prominent out there.