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B752 Mx Experience  
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Posted (8 years 5 months 15 hours ago) and read 5292 times:

Anyone out here with B752 Mx Experience.Any tips on the practical working around this Aircraft.
regds
MEL


Think of the brighter side!
64 replies: All unread, showing first 25:
 
User currently offlineMolykote From United States of America, joined Aug 2005, 1340 posts, RR: 29
Reply 1, posted (8 years 5 months 15 hours ago) and read 5287 times:

I sent you a personal message....


Speedtape - The asprin of aviation!
User currently offlineTristarSteve From Sweden, joined Nov 2005, 3999 posts, RR: 34
Reply 2, posted (8 years 5 months 7 hours ago) and read 5257 times:

The thing that I dread is the PRSOV. They are in the strut and seem to be bigger than the access hole. The right PRSOV is worse. If they dont open there is very little you can do. You cannot see the indicator, cant get a spanner on it. Its a nightmare.
One tip. When you shut the engines down the Engine bleed OFF lights come on. This is the PRSOV closing. If the PRSOVs are not both shut, the APU bleed will not open. But if you select engine start, with the APU running, the APU bleed valve opens and then the airflow pushes the PRSOV shut.
Another thing is that components on B757 are in different places. Some aircraft have pack controllers on E6 in the aft freight, and some on E3 in the fwd equip. Remember the equip bay inside the fwd freight also. Cant get ground power on? Check the fuse on the BPCU in the fwd freight.
For checking out the autopilot, get yourself a Remote MCDP Tester. Worth its weight in gold. You can then sit in the cockpit and do all the tests, instaed of running down to the MCDP in the equip bay.


User currently offlineTaguilo From Argentina, joined Aug 2005, 74 posts, RR: 0
Reply 3, posted (8 years 5 months 7 hours ago) and read 5251 times:

Quoting TristarSteve (Reply 2):
One tip. When you shut the engines down the Engine bleed OFF lights come on. This is the PRSOV closing. If the PRSOVs are not both shut, the APU bleed will not open. But if you select engine start, with the APU running, the APU bleed valve opens and then the airflow pushes the PRSOV shut.

BTW, which bus powers the Engine Bleed valves? Standby-DC or Battery?
I undestand they remain in the last position when power is removed.
If they keep open, when you add power to run the APU, reseting ENG Bleed switch Off then On wouldn't close them? (without the need to "fake" an engine start)

Tom


User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 4, posted (8 years 5 months 5 hours ago) and read 5225 times:

Hangar or line work, ?
Remember spacer and tang washer when wheel or brake changing. Take the brake bar pin out before sticking jack under to change a brake unit.
15/16" spanner for tension latch on c-ducts, watch the hinge panel if c-ducts seem tight opening, it may be tight if the hinge panel hasnt lifted. Make sure slats retracted.
EEC not on engine, in elec equip bay.
Power down aircraft if changing BVCU, otherwise you will blow new one, HAS BEEN DONE!
Theres many resets and tests to rid EICAS msgs, but you'll be forever remembering them all, just pull breakers for box relevant to system !!

theres a few !


User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 5, posted (8 years 5 months 5 hours ago) and read 5224 times:

Quoting TristarSteve (Reply 2):
For checking out the autopilot, get yourself a Remote MCDP Tester

Ideal to have the MCDP remote panel fitted on P61.

Quoting Molykote (Reply 1):
I sent you a personal message....

Thanks for the tips.The Engines are RB211-535C.

Quoting Taguilo (Reply 3):
BTW, which bus powers the Engine Bleed valves? Standby-DC or Battery

28vdc Bat Bus ENG HP BLEED VALVE & TEST.

regds
MEL



Think of the brighter side!
User currently offlineMX757 From United States of America, joined Aug 2005, 628 posts, RR: 12
Reply 6, posted (8 years 5 months 4 hours ago) and read 5215 times:

Quoting HAWK21M (Thread starter):
Anyone out here with B752 Mx Experience.Any tips on the practical working around this Aircraft.
regds

Always have a ladder handy.

I work hangar and line maintenance (avionics) on the 757-2/3. If you have any specific questions feel free to ask.



Is it broke...? Yeah I'll fix it.
User currently offlineTaguilo From Argentina, joined Aug 2005, 74 posts, RR: 0
Reply 7, posted (8 years 5 months 4 hours ago) and read 5211 times:

Quoting HAWK21M (Reply 5):
Quoting Taguilo (Reply 3):
BTW, which bus powers the Engine Bleed valves? Standby-DC or Battery

28vdc Bat Bus ENG HP BLEED VALVE & TEST.

Thank you MEL

Regards,
Tom


User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 8, posted (8 years 5 months 4 hours ago) and read 5210 times:

Quoting MX757 (Reply 6):
Always have a ladder handy

Thats true.Everything seems to be high.
How reliable are the LG Sequencing valves.

Quoting Taguilo (Reply 7):

My pleasure.
regds
MEL



Think of the brighter side!
User currently offlineLMP737 From , joined Dec 1969, posts, RR:
Reply 9, posted (8 years 5 months ago) and read 5177 times:

Quoting TristarSteve (Reply 2):
The thing that I dread is the PRSOV. They are in the strut and seem to be bigger than the access hole. The right PRSOV is worse. If they dont open there is very little you can do. You cannot see the indicator, cant get a spanner on it. Its a nightmare.

On the PW2000 powered 757's the PRSOV is located on the engine at about the 10 o'clock position. Makes the job much easier than what you have to endure on the RR powered 757's.


User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 10, posted (8 years 4 months 4 weeks 1 day 23 hours ago) and read 5168 times:

If your changing a PRSOV in a small amount of time, especially the r/h one, take the start duct out first, also, any self respecting 757 mx company will have the big spanner tool for making that gap in between the ducts close up when it seems almost impossible!
You think the PRSOV is hard!! the pre cooler is worse by far, that pylon is generally a box of tricks with jobs one time being easy another day being a pain in the ass.


User currently offlineMD11Engineer From Germany, joined Oct 2003, 13986 posts, RR: 62
Reply 11, posted (8 years 4 months 4 weeks 1 day 23 hours ago) and read 5156 times:

When doing a nose gaer lube job, don't forget the grease fitting behind the light box (lower hinge of the drag brace). You'll either need a special (homemade) fitting for your grease gun or you'll have to remove the whole box (landing and taxi lights, ground intercom panel, APU fire shut down) to get at it. I think it is the most neglected grease fitting on the 757.
BTW, PRSOV change on the PW2000 engined version is a piece of cake, the high stage valve and the PRSOV are the same part number.

Jan


User currently offlineMX757 From United States of America, joined Aug 2005, 628 posts, RR: 12
Reply 12, posted (8 years 4 months 3 weeks 6 days 12 hours ago) and read 5023 times:

Quoting HAWK21M (Reply 8):
How reliable are the LG Sequencing valves.

I have no idea, never worked them. So I would guess to say that they are pretty reliable.  Wink



Is it broke...? Yeah I'll fix it.
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 13, posted (8 years 4 months 3 weeks 6 days 5 hours ago) and read 5002 times:

Quoting MX757 (Reply 12):
I have no idea, never worked them. So I would guess to say that they are pretty reliable.

So what Jobs do you normally encounter Unscheduled Maintenancewise.
regds
MEL



Think of the brighter side!
User currently offlineTristarSteve From Sweden, joined Nov 2005, 3999 posts, RR: 34
Reply 14, posted (8 years 4 months 3 weeks 6 days 3 hours ago) and read 4992 times:

I work the B757 on a line station. We only do Daily checks and send it back to base. I find the aircraft very reliable. The FIM is extremely useful and very relevant. I have about 15 a week and in the last year have had 10 delays. Three in two weeks, a slat actuator leaking, and EDP u/s and a MLG Door actuator leaking. All 3 needed changing, and I had to wait for spares from Homebase. Other than that only minor problems.
Make sure you get a ladder the right height in your van so you can get into the E and E bay, and into the Cargo holds. The aircraft is high off the ground and if you are not 1.80m tall you will need a ladder to do the engine oils.
Talking of engine oils on the RB211 the oil cap often needs levering off, and under it is a float valve which often sticks. So pour the first can of oil in slowly. If it overflows, wait 5 mins and the float usually opens.
Hydraulics transfers from L to R system through the brakes. You can send it back by putting the brakes on with R sys and Off with L system pressurised..


User currently offlineFr8Mech From United States of America, joined Sep 2005, 5393 posts, RR: 14
Reply 15, posted (8 years 4 months 3 weeks 6 days ago) and read 4975 times:

Quoting HAWK21M (Reply 13):
So what Jobs do you normally encounter Unscheduled Maintenancewise

'Battery Charger', 'Warn Elex', 'Stab Trim', 'Pack Bite' messages all come to mind.

Brake leaks, truck positioner leaks, pylon fuel leaks. We've seen a rash of fuel pressure transmitter (PW2000) leaks.

RB211: engine surges (TPU change).



When seconds count...the police are minutes away.
User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 16, posted (8 years 4 months 3 weeks 5 days 22 hours ago) and read 4959 times:

FR8mech is right on the money there, ive had the warn elex and stab trim msgs frequently and plently of brake and truck positioner leaks.
Engine bleed problems go through phases, Hi stage lights and eng bleed lights quite common, you will get to know the 757 bleed system well with RB211 engine, im not experienced with the P+W.
APU surge valve changes are not uncommon and also the 'ovbd exhaust valve ' message, get rid of that one by doing the equip cooling test.


User currently offlineFr8mech From United States of America, joined Sep 2005, 5393 posts, RR: 14
Reply 17, posted (8 years 4 months 3 weeks 5 days 21 hours ago) and read 4951 times:

Quoting A/c train (Reply 16):
APU surge valve

Heck, I forgot all about the surging APU and the inop APU air problems.

The PW2000 is much more troublesome from a chapter 36 point of view than the RR.



When seconds count...the police are minutes away.
User currently offlineMD11Engineer From Germany, joined Oct 2003, 13986 posts, RR: 62
Reply 18, posted (8 years 4 months 3 weeks 5 days 17 hours ago) and read 4938 times:

Quoting A/c train (Reply 16):
FR8mech is right on the money there, ive had the warn elex and stab trim msgs frequently and plently of brake and truck positioner leaks.
Engine bleed problems go through phases, Hi stage lights and eng bleed lights quite common, you will get to know the 757 bleed system well with RB211 engine, im not experienced with the P+W.
APU surge valve changes are not uncommon and also the 'ovbd exhaust valve ' message, get rid of that one by doing the equip cooling test.

But most Warn ELEX messages are nuissance messages and you just have to reset Stby Power to clear them. Stab Trim Messages also often clear through shutting down and popwering up the aircraft.
Anti skid and autobrake problems were quite common as well.

We had a bunch of bleed problems on our PW2040 engined aircraft.

Most of the other stuff was, as mentioned above, APU surges, brake and truck positioner leaks, occasionally thrust reverser trouble, once I changed a rudder PCU for some electrical problem (i forgot exactly what, but IIRC it had to do with the position feedback).
I worked about 5 years with the companiy, that operated, among other aircraft types, 757-200.

Jan

[Edited 2006-03-31 04:48:46]

User currently offlineMD11Engineer From Germany, joined Oct 2003, 13986 posts, RR: 62
Reply 19, posted (8 years 4 months 3 weeks 5 days 17 hours ago) and read 4935 times:

Quoting Fr8mech (Reply 17):
The PW2000 is much more troublesome from a chapter 36 point of view than the RR.

Yes, but access to the components is easier than on the RR.

Jan


User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 20, posted (8 years 4 months 3 weeks 5 days 15 hours ago) and read 4917 times:

Quoting TristarSteve (Reply 14):
Talking of engine oils on the RB211 the oil cap often needs levering off, and under it is a float valve which often sticks. So pour the first can of oil in slowly. If it overflows, wait 5 mins and the float usually opens.

Interesting tip.

Quoting TristarSteve (Reply 14):
Hydraulics transfers from L to R system through the brakes. You can send it back by putting the brakes on with R sys and Off with L system pressurised..

The Boeing Instructors spoke of that.That was Educational  Smile

What about Start valve manual overiding.Precautions.
And APU U/S Bleedvalve.
regds
MEL



Think of the brighter side!
User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 21, posted (8 years 4 months 3 weeks 5 days 15 hours ago) and read 4918 times:

That Warn elex message was apparent one one particular airplane last summer, every time you went to start the APU when selecting BAT power on you would get the stick shaker! then you could start the APU as normal, this was always followed by a WARN ELEX message which you could clear by cycling the 2 warn elex breakers.
regds a/c


User currently offlineMX757 From United States of America, joined Aug 2005, 628 posts, RR: 12
Reply 22, posted (8 years 4 months 3 weeks 5 days 14 hours ago) and read 4911 times:

Quoting HAWK21M (Reply 13):
So what Jobs do you normally encounter Unscheduled Maintenancewise

The two most rash problems that come to mind is:

HF-We had alot of pireps along the lines of no comm and no data link with ACARS. Turns out that the problem with ACARS is that the pilots were not pushing the HF transmit overide button. The no comm problem was usally fixed with a coupler R&R.

ATC-We also had alot of pireps about ATC 1 or ATC 2 fail lights on during flight. Sometimes both failing at the same time. It turns out that Honeywell had corrupted software loaded in the transponders causing intermitent faults.

We had done a MOD here in MCO awhile back that installed EHS (Enhanced Mode S) and Honeywell upgaded the ATC transponders to incorporate the new parameters. When they did this it started to cause chronic failures throughout the 757 fleet. It was a real headache because we were doing alot of troubleshooting before it was found out the transponders were coming out of Honeywell bad.

On the A&P side of the house it seems that the line guys do alot of annulus filler changes on the RR engines. (cracks)



Is it broke...? Yeah I'll fix it.
User currently offlineSkydrolBoy From Canada, joined Sep 2003, 341 posts, RR: 2
Reply 23, posted (8 years 4 months 3 weeks 5 days 12 hours ago) and read 4897 times:

Quoting A/c train (Reply 4):
watch the hinge panel if c-ducts seem tight opening, it may be tight if the hinge panel hasnt lifted.

Thats for sure, we made it company policy to have someone watch the hinge doors when opening the c-ducts, cause if they aren't rigged properly they will catch and it makes a mess to repair. Also make sure the C-duct latch access doors are closed before operating the T/R....we found out the hard way that door is harder than the Translating sleeve....


User currently offlineFr8Mech From United States of America, joined Sep 2005, 5393 posts, RR: 14
Reply 24, posted (8 years 4 months 3 weeks 5 days 8 hours ago) and read 4888 times:

Quoting HAWK21M (Reply 20):
What about Start valve manual overiding.Precautions.

Communications with the flight deck is a must and clear the engine to the outboard side when done. Stay clear of the the inlet danger zone.

And while we are on engines. RR engine tower shaft leaks. It seems I hear about 1/week leaking.

Warn Elex can a nusiance, but if it doesn't clear 1st time around with the breakers or the IRS alingment, go right for one of the WEU power supplies. Re-seat, beat, pound or replace.



When seconds count...the police are minutes away.
25 MX757 : I forgot about that one, we had 2 here in MCO this year alone!
26 HAWK21M : Is the Tiller on both sides an option on the B752. regds MEL
27 Molykote : To answer your question from my personal message: AHAD = automatic hinge access door When this guy gets out of rig expect some damage to the C-duct an
28 HAWK21M : Thanks. regds MEL
29 Dl757md : Boeing put out a SB about the cargo door switches. Apparently there has been two incidents where the switch stuck in the close position and injured ra
30 HAWK21M : If it was Low Temperature related,That'll be a problem not encountered out at BOM. How reliable are the Red Door Safety Lt bulbs. What about APU Shut
31 Dl757md : I don't think the SB said anything about temperature. I just noted that about the switch that I changed. The switches could fail at any temperature I
32 HAWK21M : Thats Interesting. Any Experiences with APU Malfunction Fire detectors leading to Unattended mode Shutdown & Extinguishing. regds MEL
33 AvionicMech : We have had a report of one of our aircraft having the cargo door switch stick in the close position aswell, this is definately something to watch ou
34 Fr8mech : Our B757's have an auto-fire agent discharge system.
35 Post contains images Aogdesk : You certain about that? I know the A300 has auto discharge, but I didn't think that the B757 did....thought you had to hit it from the left NLG panel
36 Fr8mech : Yup. Nowhere near the tech manuals at the moment, but as I recall, you had something like 30 secs to either hit the fire shutdown (pull handle or hit
37 AvionicMech : I guess I had better look that up as well but I was almost certain that it would not auto-discharge. I will look tomorrow if I remember.
38 ATLAMT : It depends on the fire suppresion system. You can have either a dual bottle which I believe dosen't auto-discharge. Or a single bottle auto-discharge
39 HAWK21M : In Unattended mode the B752 does have Auto Fire Extinguishing for the APU. regds MEL
40 Atlamt : From the AMM: Effective on the following aircraft only: AIRPLANES WITH DUAL APU FIRE EXTINGUISHER BOTTLES; when the airplane is in flight and a fire i
41 HAWK21M : What about Grd mode with Dual bottles.I presume it should have the capability to discharge the Extinguisher in Unattended mode. regds MEL
42 ATLAMT : From what we were told dual bottle a/c will not discharge automatically. Someone has to discharge the system. The apu will shutdown if a fire is detec
43 Post contains images AvionicMech : I looked it up in the AMM today and sure enough the bottle will fire automatically on detection of a fire and obviously shut down the APU. But I also
44 HAWK21M : It does not make sense then.If Fire is the concern.Then Two bottles or One Bottle.Unattended mode should fire both types. We were taught on Single AP
45 CdfMxTech : Put cap on, then try to pull of as quick as possible. Usually clears the air lock.
46 HAWK21M : How quickly can the Primary Heat Exchanger,Secondary Heat Exchanger & Plenum Diffuser unit be Dropped. regds MEL
47 MD11Engineer : We had a bit of problem with cold soaked APUs in winter. Often, when trying to start them you will get a "low Oil Pressure Fail" auto shutdown and fau
48 A/c train : You can drop the complete unit using the IDG stand in about 2 hours, both heat exchangers ram air inlet and ACM plenum, easy little job but it looks l
49 MD11Engineer : IIRC = If I Remember Correctly Jan
50 AvionicMech : Another one to remember, but this is true for most aircraft I would have thought is to make sure the electrical power source is not swapped during an
51 A/c train : Ive just been reminded about doing the stall warning test when the Hyd pumps are on, the slats will come out and if you lock yourself out of the fligh
52 HAWK21M : This Autoslat Function was told to us in Training. Pls elaborate. regds MEL
53 SkydrolBoy : By shutting down the apu, it will turn off power and unlock that fancy new bulletproof door if it has an electronic lock.
54 HAWK21M : What is the Circuit like for U/s APU in Flight. regds MEL
55 Fr8Mech : No issue inflight. The aircraft is still powered. What Skydrolboy is saying is that if the aircraft is on the ground on APU (or ground powe, I assume
56 HAWK21M : I understood what was meant.What I was curious was.Was the solenoid only de energized on Grd with no power.But in Air has no effect.What caused it.Th
57 A/c train : HAWK21, there is a switch under a red guard in the flight deck witch you switch on to lock the door, kill the power on the nose leg, you de-energise t
58 HAWK21M : Whats stops an APU shutdown in Flt from Unlatching the Locked door then. regds MEL
59 A/c train : The two great big 110 lb IDG's on both engines may do it ?
60 Fr8Mech : Hawk, the key is power. Power on, door stays locked. Power off, door is unlocked. No need for a/g sense. APU is just a source of power.
61 AvionicMech : Would it not be easier and probably quicker to just enter the access code into the keypad and wait for it to go through the auto-unlock sequence?? Not
62 HAWK21M : Ok.So presuming on Ground,APU off,but GPU selected.The Door won't unlock. regds MEL
63 SkydrolBoy : Yank the powercord....
64 HAWK21M : Ok.Thanks. regds MEL
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