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HAWK21M
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B752 Experienced Folks

Tue Feb 05, 2008 11:03 am

Anyone out here with B752 & RB211-535 Experience in Flight ops & Maintenance.
Compared to the type just in the country recently.Abroad most folks will have worked on these types for years.Just looking to get some valuable tips which no manual can teach for those with the experience on the type either through this forum or Email if possible.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
LMP737
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RE: B752 Experienced Folks

Tue Feb 05, 2008 4:21 pm

When they get older hydraulic leaks start to become an issue. Changing spoiler actuators is easy money, much easier than an MD-80 spoiler actuator. Bite check on on the APU ECU can be hit or miss sometimes. This is just off the top my head. Just got off a night shift so I'm a little punch drunk.
Never take financial advice from co-workers.
 
A/c train
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RE: B752 Experienced Folks

Tue Feb 05, 2008 4:50 pm

- If you get no EGT rise on start and no FF, get an ally drift and hit the P+D solenoid on the FFG, you will hear the BOOM of fuel flow as the solenoid unsticks. Then get on the airplane and do the same thing downroute.

- Us an ally podger on the floating beam when changing the C-Ducts, you will be forever hitting it to get it to jump over

- Ratchet strap the carriage to the flap track when cnanging flap screwjacks, if the flap moves you will be forever getting the bushes back in

- When changing the FFG on a turnround, just take everything you can off to make it easier, make note and write it down on worksheets. Wrap rags around your wrists and accept your going to get wet and get stuck into it.(especially that big pipe between tbe FFG and HP fuel pump.

- Buy a 5/16 wobbly socket if you havn't already got one

- Dont forget to swap the EDP quick release couplings over when changing an EDP, ive seen it done.

- Clean the spigots and grease them on the crocodile fairing, you wont look like such a butcher hitting the thing back on.

- ELEV PCU messages may just require adjustments of the pogo rods, use the PCU monitor as is sometimes good.

- Warn ELEX messages, 2 c.bs on either overhead panel

- STAB TRIM, cycle the stab and bite check the SAM's on the CSEU's

.... you could go on forever but heres a few, You will learn yourself from experience more than anything, im on 737 NG's and 319/320/321 now so I will miss the 75.
 
Mender
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RE: B752 Experienced Folks

Tue Feb 05, 2008 5:14 pm

If the thrust reverser actuators develop a hydraulic leak clock out and go home ;0)
 
Tristarsteve
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RE: B752 Experienced Folks

Tue Feb 05, 2008 5:29 pm



Quoting A/c train (Reply 2):
- Warn ELEX messages, 2 c.bs on either overhead panel

- STAB TRIM, cycle the stab and bite check the SAM's on the CSEU's

Funny you put those together, because I had them together last week, together with FSEU Something!
If after Warn Elex CB reset, and then a stall warning test, and it doesn't clear go down into the E and E bay and climb in and left towards the nose. On the floor is a little box with red digits on it. It is the warn elex bite module. It gave me a good clue that the warn elex message was caused by the FSEU, and looking at the SAMs, so was the Stab msg.

Now what you need to know is that there are 3 FSEU in the fwd freight, they are all interchangeable, but they do different jobs. So what you do is interchange them. I changed 1 with 2, no good them 2 with 3. Then it all worked.
I think FSEU3 does indication only, so if say FSEU is u/s you can put it in nbr 3 and it isn't being used.
 
A/c train
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RE: B752 Experienced Folks

Tue Feb 05, 2008 5:56 pm

I have always found the FIM on the 757 to be very good as it should be on most airplanes, it generally sends you down the right path.
Good one about the FSEU's Tristar. do yours use -40 's ?
Always follow the BITE check procs on the front of the box aswell, switch position in the flight deck may be very relevant for BITE checks. This may sound like egg sucking put ive seen many people just press the button, get the result they want, close up and put the kettle on. No good sir !
I think human factors calls it conformation bias !

RB211 c-duct actuators, do NOT bend the pipes to much, they are ally and will crack, then you have leaks as mender said. Clock out and go home.

PRSOV changes, there is a tool made up which has a cutout bigger than the diameter of the connecting ducts to the valve, it has a teflon block on the side for levering against the panel cutouts to get the ducts to close up to get the clamps on, it sometimes isnt needed.

HI STAGE light, re set the button on the hi stage valve and go do a run. FIM from there.

BLEED light is an ovht condition, fan air valve , 490 , 450 sensors etc .......

Fluctuating duct press ive found is usually loose sense lines or Reverse flow controller.

The biggest and best rule for troubleshooting from my experience so far is to use the FIM and the advice more experience folk give you, be prepared to be WRONG from time to time, accept it and learn from it.


For ANY messages, before doing anything, check the pstn of the standby power switch.
 
Tristarsteve
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RE: B752 Experienced Folks

Tue Feb 05, 2008 6:10 pm



Quoting A/c train (Reply 5):
The biggest and best rule for troubleshooting from my experience so far is to use the FIM

Agreed.
I have worked B757 since 1988, but only had a course in 2002. In all those years I found the FIM gave me all the info needed. I stilll have my set of three hardbacks, which must be 5 years out of date, but save ages! (Then having the reference I look it up in my on-line manual).

Use the FIM for locations and CBs. Cycle the CBs and do the Verify. Clears 90pc of messages.

remember the Instrument Comparator. For Roll disagree and pitch disagree etc., on nearly all aircraft reset CB F7 and the comparator usually clears the message.

Another common one is BATT Charger. Standby power check will clear this.

But remember always go and Auto then erase on the buttons.

By the way MEL, on our aircraft the IRU are the same pt nbr on B757 and B737-400. One day I robbed a B757 (3 IRU) to fix a B734.(2 IRU)
 
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HAWK21M
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RE: B752 Experienced Folks

Wed Feb 06, 2008 8:58 am

Fantastic Info folks.very valuable things I'd def remember.

Quoting A/c train (Reply 2):
- Warn ELEX messages, 2 c.bs on either overhead panel



Quoting TristarSteve (Reply 4):
On the floor is a little box with red digits on it

Had this a few nights ago.Had to use the MEC Stall wx reset,as the Cb & test sw did not erase the message.

Quoting TristarSteve (Reply 4):
I think FSEU3 does indication only

Thats true.

Another debatable question is the "Why" type which no manual can provide except the manufacturer.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
777wt
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RE: B752 Experienced Folks

Fri Feb 08, 2008 2:19 am



Quoting A/c train (Reply 5):
PRSOV changes, there is a tool made up which has a cutout bigger than the diameter of the connecting ducts to the valve, it has a teflon block on the side for levering against the panel cutouts to get the ducts to close up to get the clamps on, it sometimes isnt needed.

Where can I get that tool?
 
A/c train
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RE: B752 Experienced Folks

Fri Feb 08, 2008 8:07 am

Dont stand and gaze, Auto erase !!......... not sure where you can get it to be honest, ill ask around for you. Going to sit my very last B1 licence exam now !
 
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HAWK21M
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RE: B752 Experienced Folks

Sat Feb 09, 2008 8:00 am



Quoting A/c train (Reply 9):
Going to sit my very last B1 licence exam now !

Best wishes.

About tools.....There are some amazing types of tools in Aviation.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
A/c train
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RE: B752 Experienced Folks

Sat Feb 09, 2008 10:12 am

hi HAWK, ive passed my last exam and now finished the full B1 licence !!! , im chuffed to bits at the mo !
 
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HAWK21M
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RE: B752 Experienced Folks

Sat Feb 09, 2008 6:34 pm



Quoting A/c train (Reply 11):

hi HAWK, ive passed my last exam and now finished the full B1 licence !!! , im chuffed to bits at the mo

Congrats.....I can just imagine how thrilled you must be.
If you were in BOM,you'd need to buy some drinks  wink 
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
fr8mech
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RE: B752 Experienced Folks

Sat Feb 09, 2008 8:42 pm

As a US A&P I find it interesting to look at the separate licensing requirements in different countries. I was able to work on a B757 (or any other US registered aircraft) immediately after being granted my license, and of course, being employed by the appropriate entity. I did have to receive 2 weeks of company training in order to qualify for the 2 more weeks of avionics training (fleet specific) required to release a CATIII aircraft and the further training for run up/taxi.

To the subject at hand:

-The RB211 PRSOV sucks, but we've found it to be extremely reliable, except in the last couple of months. Big uptick in removals.
-MCDP is your friend. Learn to use it. Understand what it is telling you.
-The FIM is your best friend. Hands down, the best I've been exposed too.
-The SSM is like your best friend's hot sister. You always want her around you, but you're too scared to talk to her (especially if you're afraid of prints). Don't be afraid, she can tell you a lot.
-Before you auto-erase, take a look at ALL you system's screens and see if some data has been captured.
-Don't overservice the IDG (goes for any IDG). If you're in doubt, follow the AMM to the letter. The drain hose is your friend.
-Left to right, and the reverse, transfer of hydraulic fluid is simple and a whole lot quicker than normal servicing.
-A reported L/R hydraulic system transfer is not necessarily a problem. It may be an issue with how the crew is sequencing hydraulic power.
-WARN ELEX is a nuisance message 99% of the time. Pull the 2 breakers on the P11 (?), wait 30 seconds, push them in simultaneously. 3 or 4 seconds later it should be gone. If not, align the IRU's (10 minutes). The message may go away anytime during alignment. If it's still there, hit the stall warning, 1 system at a time. If it's still there, you got the 1%.
-Do an AFOLTS test at least 3 times before deciding you have a problem.
-Get used to seeing: Stab Trim, Spoilers and APU Bite on the maintenance page. Each will require the specified BIT to clear. Pay attention if you keep getting the same message on the same aircraft. It's talking to you.
-Switch between EICAS computers if something doesn't look right. Do the EICAS BIT and look for difference in the discrete codes. They will lead you to some of those chronic issues.
-Don't trip the battery with the APU running. It will shutdown after cool down.
-Ctrl/Alt/Del works great on this aircraft. 30 - 45 seconds will do wonders for messages.
-You can, if you so choose, make the aircraft completely dark, with the APU running, for those stubborn messages. Take the APU generator offline, then knock off the battery. BEWARE, you have no fire protection at the APU.
-If you come across a right ACMP that will not shut-off, look at the brake source switch.

There is so much more. Bring up some specific issues and we can all work through them. It is a user friendly aircraft for 70/80's technology.
When seconds count...the police are minutes away.
 
A/c train
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RE: B752 Experienced Folks

Sat Feb 09, 2008 10:58 pm

hi Fr8mech,
as an unlicenced aircraft mechanic, you can hold no CRS. You can sign a pre flight inspection and thats all. To be able to certify aircraft you require a PART-66 licence in various categories.
There are many very experienced aircraft mechanics in the UK who are unlicensed, the exams are very hard and there are so many of them ! The essays are particularly tricky.
The licence ive just completed is the full B1- Mechanical licence, enables me to certify Airframes/engines and electrics. Avionic LRU changes requiring simple tests to prove there serviceability. But before I have any authorisation I need a type course that will take an average of 6-8 weeks.
 
fr8mech
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RE: B752 Experienced Folks

Sat Feb 09, 2008 11:39 pm



Quoting A/c train (Reply 14):
you can hold no CRS

What is that?

Personally, I don't see the advantage to all these different levels. I understand the theory but in practical use, it's constraining to the employer and the mechanic/engineer/technician. I like the fact that I can have one mechanic troubleshoot and repair any issue on the aircraft.

I understand that newer aircraft require more specialized knowledge and skills, but those skills and training should be an enhancement to current ratings, not a constraint or impediment.

Too me, this just seems like a big government social program. Why have 1 mechanic fix an airplane when you can, through regulation, force an operator to hire 3 or 4 different guys to do parts of the whole? It's a big, government mandated union shop. Just my way of thinking.

Quoting A/c train (Reply 14):
The essays are particularly tricky.

Essays!? An example, please. Are you expected to know all without reference? I encourage all my folks, myself included, to hit the book whenever they have an issue. Whenever I have the opportunity to question someone as to their ability, I don't ask "what system on a B757 powers the alternate brakes?" I ask, "Go look up the braking system on the B757 and give me a brief summary, including primary, alternate and reserve, if installed. You have 5 minutes."
If the person knows how to navigate a maintenance manual, he will have no problem finding the answer.

Off soapbox.
When seconds count...the police are minutes away.
 
A/c train
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RE: B752 Experienced Folks

Sun Feb 10, 2008 9:47 am

basically the way EASA have worked it is as follows. There are four licence categories,

- A licence- Mechnical line mechanics licence, enables you to sign wheels, brakes, filaments, pre flight/daily checks and other simple tasks.

-B1 licence - Mechanical, enables you to certify all airframe engine tasks, including simple wiring repairs and defects. Simple avionic LRU changes

- B2 licence- Avionic licence, Navs, comms.

- C licence - Base maintenance check CRS certifier
 
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HAWK21M
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RE: B752 Experienced Folks

Sun Feb 10, 2008 10:51 am



Quoting Fr8Mech (Reply 13):

Very Valuable tips.Thanks.

Quoting Fr8Mech (Reply 15):
Quoting A/c train (Reply 14):
you can hold no CRS

What is that?

CRS :- Certificate of Release to Service,needs to be issued every time a DI or higher check is carried out or a Transit check carried out with some unscheduled Mx work.

Quoting A/c train (Reply 16):
basically the way EASA have worked

We'll be adopting the EASA system in 2008/09.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
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RE: B752 Experienced Folks

Sun Feb 10, 2008 4:59 pm



Quoting Fr8Mech (Reply 15):
Personally, I don't see the advantage to all these different levels. I understand the theory but in practical use, it's constraining to the employer and the mechanic/engineer/technician. I like the fact that I can have one mechanic troubleshoot and repair any issue on the aircraft.

I have worked under both systems, and they both have their advantages.
I have an EASA B1 licence. I work alone on the line. I can rectify and release just about anything without referring to main base. If I have a problem I call my maint control and they can help me out. But they cannot issue certification. That I do myself iaw the aircraft manuals. If the manuals do not cover what I want to do, I can get an alleviation to do something different, but this is very complicated and very rare nowadays. I haven't used it in 4 years.

10 years ago I worked for a US airline. I had a 10 day course from them (compared to a European 50 day course) and could do anything on the aircraft, but was expected to call maint control for advice. I definitely could not raise a placard without advice. I could get very detailed tech advice from them and they even told me to quote their names in the log book.

Both systems work. I found the US system better with a complicated defect, I got better help. I find the EASA system better with smaller defects, I can defer items on my own without waiting for a reply from the centre.
 
LMP737
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RE: B752 Experienced Folks

Thu Feb 14, 2008 1:33 am



Quoting A/c train (Reply 5):
PRSOV changes, there is a tool made up which has a cutout bigger than the diameter of the connecting ducts to the valve, it has a teflon block on the side for levering against the panel cutouts to get the ducts to close up to get the clamps on, it sometimes isnt needed.

The one nice thing about PW2000 powered 757's is that the PRSOV is on the engine and not in the pylon. Scraped up my knuckles a number of times taking out a PRSOV out of RB211 powered 757. Along with practicing my profanity skills.  Wink
Never take financial advice from co-workers.
 
MX757
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RE: B752 Experienced Folks

Thu Feb 14, 2008 10:39 am

The EGPWS computer can help with troubleshooting a lot of chronic navigation problems. It is wired to a lot systems; I've found that checking current faults and flight faults helps me narrow down bad LRUs or wiring.
Is it broke...? Yeah I'll fix it.
 
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HAWK21M
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RE: B752 Experienced Folks

Thu Feb 14, 2008 11:18 am



Quoting LMP737 (Reply 19):
The one nice thing about PW2000 powered 757's is that the PRSOV is on the engine and not in the pylon.

Is the Pylon narrower for the P&W Engines?

Quoting MX757 (Reply 20):
The EGPWS computer can help with troubleshooting a lot of chronic navigation problems

Interesting point to remember.

A related query on the type.Can the Fuel qty of board just after stopping refuelling & around 10-20 mins later drop by 200-300kgs.Shouldn't the processor show an error code if the volume is not mantained ideally.

Also can pitch up of 2-3 degrees on ground cause the fuel total on board to vary?

regds
MEL.
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
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RE: B752 Experienced Folks

Thu Feb 14, 2008 1:04 pm



Quoting HAWK21M (Reply 21):
related query on the type.Can the Fuel qty of board just after stopping refuelling & around 10-20 mins later drop by 200-300kgs.Shouldn't the processor show an error code if the volume is not mantained ideally.

I don't find this a problem on B757. We have kg indications, and I find the B757 is the most accurate aircraft to refuel. If you want 12000, you dial up 12000, and it stops at 12000, and stays there. The B767 is different. That always drops 2-300kg, usually after you close the refuel panel and walk up to the flight deck, but not the B757.
 
777wt
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RE: B752 Experienced Folks

Thu Feb 14, 2008 5:00 pm

There's also the oil presure sensor or ground switch on the #2 engine that does not get power to it unless the engine is running, not the same setup as engine #1...P&W powered I think it was.
 
tdscanuck
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RE: B752 Experienced Folks

Thu Feb 14, 2008 6:39 pm



Quoting HAWK21M (Reply 21):
Can the Fuel qty of board just after stopping refuelling & around 10-20 mins later drop by 200-300kgs.

Yes. The FQIS on all aircraft is directly measuring volume. This is converted to mass via measured density. The density is measured by a densitometer and/or compensator, which are in the bottom of the tanks. Since fuel density changes with temperature, if you uplift fuel with a different temperature or density than what's in the tank sump, it will take some time for the fuel in the sump to equalize and compensator/densitometer to adjust to the new density. While it's doing it, the indicated quantity will crawl around.

Quoting HAWK21M (Reply 21):
Shouldn't the processor show an error code if the volume is not mantained ideally.

Nope. The processor has no knowledge of what the rest of the aircraft is doing. It can't tell the difference between fuel being pumped out of the tank and quantity changing due to density/temperature changes. It will throw an error if the sensed density or quantity goes out of range. It also does continuous electrical diagnostics and will throw an error if it finds a bad probe or wiring.

Quoting HAWK21M (Reply 21):
Also can pitch up of 2-3 degrees on ground cause the fuel total on board to vary?

The actual quantity, no. The indicated quantity, yes. The FQIS has no attitude input; it uses the point samples from the fuel probes and a software model to extrapolate to total fuel volume in the tank. It's pretty good but not perfect, so you see some indicated quantity change with pitch and roll.

Tom.
 
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RE: B752 Experienced Folks

Thu Feb 14, 2008 7:02 pm



Quoting Fr8Mech (Reply 15):
I encourage all my folks, myself included, to hit the book whenever they have an issue.

In my industry, (where people don't die, but we can lose millions of dollars.. which is apparently worse, for some reason), our exams are usuallly - mostly - geared toward ensuring that the applicant understands the subject matter and knows how to use outside sources.

If an exam demands that you know minute detail, then it was probably written by some idiot tech writer that had the manual in front of them to compose it, and it's therefore worthless.

After all - if the manuals aren't available, you can't ask someone else, and you can't even use a satellite phone to call someone to find an answer, then you're probably in the middle of a nuclear war and standards are the least of your concerns.

So I agree with you completely. Use the resources available and accept that you can't learn everything parrot-fashion.
Todos mis dominós son totalmente pegajosos
 
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HAWK21M
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RE: B752 Experienced Folks

Thu Feb 14, 2008 7:03 pm



Quoting TristarSteve (Reply 22):
The B767 is different. That always drops 2-300kg, usually after you close the refuel panel and walk up to the flight deck, but not the B757

We have something on one B752.Where the fuel qty actually drops 200-300kgs after 20 mins of refuelling.So we double check by Calculation of litres.So actually the total fuel filled is 200-300kgs higher indicated,before it drops back to normal.

Quoting Tdscanuck (Reply 24):
The actual quantity, no. The indicated quantity, yes.

Since its a freighter,the entire Main deck is offloaded & there is a definite Pitch variation on ground.I'm surprised as should the compensator & varied distributed capacitance probes cater to this.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
tdscanuck
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RE: B752 Experienced Folks

Thu Feb 14, 2008 8:11 pm



Quoting HAWK21M (Reply 26):

Since its a freighter,the entire Main deck is offloaded & there is a definite Pitch variation on ground.I'm surprised as should the compensator & varied distributed capacitance probes cater to this.

The compensator can't recognize pitch or roll, so it can't help. The probes don't either...they're designed assuming a normal attitude and can't tell when the fuel isn't level relative to the probe. The FQIS processor has a software model of the tank and it's the part that compensates for attitude changes, but it's not perfect because the actual tank geometry is *way* more detailed than the software model in the FQIS. The FQIS should stay within tolerance (usually +/- 2.5%) for attitude changes, but it won't stay rock steady.

Tom.
 
fr8mech
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RE: B752 Experienced Folks

Thu Feb 14, 2008 11:33 pm



Quoting 777WT (Reply 23):
There's also the oil presure sensor or ground switch on the #2 engine that does not get power to it unless the engine is running, not the same setup as engine #1...P&W powered I think it was.

Not quite sure what you're talking about here, but my pet peeve: where in the AMM, FOM, AOM, etc. do you ever see any engine numbered on a B757 (or B767 for that matter). It's Left & Right, not 1 and 2.
When seconds count...the police are minutes away.
 
LMP737
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RE: B752 Experienced Folks

Thu Feb 14, 2008 11:57 pm



Quoting HAWK21M (Reply 21):
Is the Pylon narrower for the P&W Engines?

I don't think so.
Never take financial advice from co-workers.
 
tdscanuck
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RE: B752 Experienced Folks

Fri Feb 15, 2008 1:03 am



Quoting Fr8mech (Reply 28):
where in the AMM, FOM, AOM, etc. do you ever see any engine numbered on a B757 (or B767 for that matter). It's Left & Right, not 1 and 2.

I don't see it in the AFM or FCOM, but it's that way in the AMM (e.g. 06-30-00, Figure 205).

Tom.
 
fr8mech
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RE: B752 Experienced Folks

Fri Feb 15, 2008 3:55 am



Quoting Tdscanuck (Reply 30):

I don't see it in the AFM or FCOM, but it's that way in the AMM (e.g. 06-30-00, Figure 205).

Very nice. I never saw that before. It is arguable that since that figure is specific to the RB211, that it was put in the book by RR. It appears that the rest of the book refers to Right and Left.
When seconds count...the police are minutes away.
 
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HAWK21M
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RE: B752 Experienced Folks

Fri Feb 15, 2008 7:10 am



Quoting Tdscanuck (Reply 30):
I don't see it in the AFM or FCOM, but it's that way in the AMM (e.g. 06-30-00, Figure 205).

Thats true.
Our B737s are reffered to as #1 & #2 while on the B757s its Left & Right.
Took some time to get used to  Smile

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
777wt
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RE: B752 Experienced Folks

Fri Feb 15, 2008 2:03 pm



Quoting Fr8mech (Reply 28):
Not quite sure what you're talking about here, but my pet peeve: where in the AMM, FOM, AOM, etc. do you ever see any engine numbered on a B757 (or B767 for that matter). It's Left & Right, not 1 and 2.

I had to look at a 757 again to refresh my memory, it was the l/h aileron and l/h elevator position pointer not showing up on the EICAS.
You could check the flt controls, hyd system, reset the cb's, do a BITE check on the flt control computers and it will not fix it.

Reset the #1 engine oil pressure cb and the flt control indicator comes back. the flt control gets it's reference volts from the oil pressure switch.
 
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HAWK21M
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RE: B752 Experienced Folks

Fri Feb 15, 2008 2:18 pm



Quoting 777WT (Reply 33):

Reset the #1 engine oil pressure cb and the flt control indicator comes back. the flt control gets it's reference volts from the oil pressure switch.

Remember that one from training very well.
Even the reference voltage is supplied to the Hyd press readings on the status page.Loss of the reference voltage signal causes the indicators to read 4000psi & loss of the pressure signal will cause a blank reading.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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HAWK21M
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RE: B752 Experienced Folks

Mon Dec 29, 2008 4:00 pm

Anyone faced an issue with the Fuel qty system on the type yet.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
tdscanuck
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Joined: Wed Jan 11, 2006 7:25 am

RE: B752 Experienced Folks

Mon Dec 29, 2008 6:49 pm



Quoting HAWK21M (Reply 35):
Anyone faced an issue with the Fuel qty system on the type yet.

Which one? Some very early 757's have the Honeywell FQIS, which was notoriously flaky. They soon switched to a Goodrich system, which works a lot better but still has its foibles.

Tom.
 
fr8mech
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RE: B752 Experienced Folks

Tue Dec 30, 2008 1:28 am



Quoting HAWK21M (Reply 35):
Anyone faced an issue with the Fuel qty system on the type yet.

The later fuel quantity systems are very reliable. I can't recall a problem in the last several years that wasn't related to the indicator itself.
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HAWK21M
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RE: B752 Experienced Folks

Wed Dec 31, 2008 12:42 am



Quoting Tdscanuck (Reply 36):
They soon switched to a Goodrich system, which works a lot better but still has its foibles.

Any details on this upgrade.Was it only a FQIS Processor replacement or something more?
regds
MEL...
I may not win often, but I damn well never lose!!! ;)
 
tdscanuck
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Joined: Wed Jan 11, 2006 7:25 am

RE: B752 Experienced Folks

Wed Dec 31, 2008 2:01 am



Quoting HAWK21M (Reply 38):

Quoting Tdscanuck (Reply 36):
They soon switched to a Goodrich system, which works a lot better but still has its foibles.

Any details on this upgrade.Was it only a FQIS Processor replacement or something more?

I think is was a wholesale gutting...new probes, new processor, and new harness. The harness was the biggest problem, as I recall, but that was really before my time so I'm hazy on the details.

The Goodrich FQIS is pretty well behaved...if the processor goes bad it's pretty obvious and easy to replace. The indicator is probably the most flaky component but, again, that's pretty obvious and easy to replace. A bad or (worse) loose probe is a royal pain, and a harness fault is extremely difficult to pin down with certainty.

Tom.
 
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HAWK21M
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RE: B752 Experienced Folks

Wed Dec 31, 2008 11:40 am



Quoting Tdscanuck (Reply 39):
a harness fault is extremely difficult to pin down with certainty.

Harness damage would be due to aging & likely in older aircraft.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
tdscanuck
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Joined: Wed Jan 11, 2006 7:25 am

RE: B752 Experienced Folks

Wed Dec 31, 2008 6:07 pm



Quoting HAWK21M (Reply 40):
Harness damage would be due to aging & likely in older aircraft.

FQIS harnesses usually age pretty well if you leave them alone. The fuel tank is actually a very good environment for wires (from a longevity point of view). It's dry, relatively clean, and constantly washed in solvent. The major issue is that the wires get stiff as they age and, as soon as you start troubleshooting the harness (especially a shake test) you take a harness that may have been OK and open up every crimp and loop in the thing and introduce all kinds of issues.

Tom.

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