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Help Requested On Digital Fuel Qty Ind.  
User currently offlinePopee From Pakistan, joined Feb 2001, 151 posts, RR: 0
Posted (12 years 11 months 3 weeks 2 days 18 hours ago) and read 1729 times:

Our B747-300 are fitted with Smiths Digital FQI. The MM says that the P8 to P11 values are self ascertained by the FQI and are not to be given to DCTU. Whereas P1 to P7 values are to be manually fed to DCTU. P1 to P7 manually feeding is OK. Problem is we are also manually feeding P8 to P11 causing a lot of problems, such as U/R, O/R, early cutout i.s.o at full volume and so on. How will the FQI itself read the values of P8 to P11, the manual does not say about it. Can any one help me, please.

As usual bundle of thanx in advance.

7 replies: All unread, jump to last
 
User currently offlineCdfmxtech From United States of America, joined Jul 2000, 1341 posts, RR: 27
Reply 1, posted (12 years 11 months 2 weeks 6 days 11 hours ago) and read 1671 times:

I am not familiar with the Smiths on the B743, but ASSUMING it is the same as the ones we have on our Classic 37s, all values are fed to the Fuel Qty Indicator. The microprocessor then talks to the DCTU, which corrects (trims/calibrates) the values based on the seetings entered when the guage was installed.

have you tried looking at a schematic or WDM??


User currently offlinePopee From Pakistan, joined Feb 2001, 151 posts, RR: 0
Reply 2, posted (12 years 11 months 2 weeks 5 days 15 hours ago) and read 1647 times:

Thanx Cdfmxtech !

Assuming the sys to be same, can you let me know that did you ever notice any such calibration by observing change in the input values. I am asking so because I never noticed any change in the values that I have set once, they remain as they are.


User currently offlineDc10hound From United States of America, joined Dec 2000, 463 posts, RR: 5
Reply 3, posted (12 years 11 months 2 weeks 5 days 5 hours ago) and read 1634 times:

Popee-
I Have a copy of Smiths Industries CMM (28-44-25) for the DCTU. Page 7 lists the parameters to be entered into the unit:

P01: Readout in Kg/Lb
P02: Empty Tank Capacitance
P03: Fuel Density
P04: VTO Fuel Weight
P05: Compensator Capacitance (Full A/C Cal.)
P06: VTO Shutoff, Valve Delay
P07: Refuel Temperture (Min.)

P08: Dry Compensator Capacitance

P09: Dry Tank Capacitance

P10: Wet Compensator Capacitance

P11: Full Tank Capacitance

As you can see, P2,P4-P6 and P8 thru P11 will vary with aircraft type and the specific tank being measured.
The values entered are critical to correct operation of the system. The information entered will be retained in memory. The AAL DC-10 MM, 28-41-10 calls out specific values for all the parameters. Your 747 MM should also. If it doesn't, you need to call Smiths Industries, quick!!  Smile



"Eagles soar. But weasels never get sucked into jet intakes.."
User currently offlinePopee From Pakistan, joined Feb 2001, 151 posts, RR: 0
Reply 4, posted (12 years 11 months 2 weeks 4 days 17 hours ago) and read 1624 times:

Thanx for the ref u gave. I already have that with me. The problem is MM says that P1 to P7 values are to be fed manually. So far so good. P8 to P11 are ASCERTAINED by DCTU itself (how ? no one knows, nor the MM says. I am interested in the second part of how DCTU is going to get these values (P8 - P11) itself. Do u have any experience on it ?

Once again Thanx in advance.


User currently offlineDash8tech From United States of America, joined Jul 1999, 732 posts, RR: 5
Reply 5, posted (12 years 11 months 2 weeks 4 days 12 hours ago) and read 1623 times:

Ours in the F-28 goes no farther than P08, sorry!

Interesting conversation though, one of the better tech questions!

Cheers!


User currently offlineDc10hound From United States of America, joined Dec 2000, 463 posts, RR: 5
Reply 6, posted (12 years 11 months 2 weeks 4 days 7 hours ago) and read 1620 times:

Popee-
As far as I can tell, ALL of the parameters MUST be manually fed to the DCTU, and they must be correct for the given A/C. This is the case for AAL DC10s. B747 and F28 might be different though...
I would suggest that you contacting the following:

Smiths Industries Aerospace And Defence Systems Ltd
Product Support, Northolt Road
Heathrow Airport, London
Hounslow, England TW6 2LW
Tel: 081-759-9121
Telex: 25662

or

Smiths Industries Aerospace and Defence Systems Inc
Product Support, North America
P.O. Box 9013
Clearwater, FL 34618
USA
Tel: (813) 539-1631
Telex: 6815304



"Eagles soar. But weasels never get sucked into jet intakes.."
User currently offlinePopee From Pakistan, joined Feb 2001, 151 posts, RR: 0
Reply 7, posted (12 years 11 months 2 weeks 2 days 12 hours ago) and read 1605 times:

Thanks Guys.
Dc10hound, greatful for your addresses. But do you have an email for any of them to contact ?


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