738: heat exchanger for hydraulic fluid in the tank, smart?

[Gnirren]

Seems to me if there's a leak, it will contaminate all the fuel in that tank. Or maybe this can't happen through the design?

[catchup]

What about the A340 IDG cooler? As far I remember, same thing.

[barit1]

GE has used fuel as cooling medium for engine oil for many years, with good success.

[Dan Winterland]

747s also use fuel to cool the Hyd systems contents. This is a martix of pipes in the tank itself. As the fuel burns off, the hyd fluid temps of the 1 and 4 systems increases as there is less fuel in these tanks.

Ths IDG cooling is done by fuel flowing to the engine and not the fuel in the tank.

Incidently, If you see the oil contents increasing on many engines, this could be an indication that there is a leak between the fuel and oil in the oil cooler/fuel heater. This is generally acknowledged to be a bad thing.

[matkat]

In the B747 the cooler matrix is covered in sealant to minimise leak/contamination possibility in 10 years in B747 maintenance I have never known it to leak,in the event of the fuel cooled oil cooler leaking, I have seen these leak several times not only does the oil tank appear to be gaining oil the colour changes(which is obvious in the sight gauge) and there is a very distinct smell of fuel when You remove the filler cap it is certainly one You will not miss

[rigpiggy]

Seems to me if there's a leak, it will contaminate all the fuel in that tank. Or maybe this can't happen through the design?

It's Jet fuel the amount of contamination would be minimal/insignificant. contamination of the hydraulics would be more detrimental

[Bus429]

757 has same setup regarding hydraulic fluid cooling

[Rainboe]

Where you have a lot of fuel needing a tremendous amount of heating, and hydraulic oil needing a tremendous amount of cooling, it seems natural somehow to put them together, just like most jets flying today! The 738 is no exception.

[bafanguy]

727...same thing.

[Ranger 1]

BAC 1-11 had the same set up for cooling Hydraulic fluid, also if I can remember correctly Concord used fuel to cool Hydraulics as well.:ok:

[Itswindyout]

Did the conc use fuel to cool the leading edges, or was it the leading edges that warmed the fuel...?????
Windy

[barit1]

Supersonic cruise always presents a significant systems-cooling problem. The mass of fuel in the tanks is about the only sizable heat sink available, and by the end of a cruise segment the fuel has picked up a lot of heat, both from Mach ram rise and from oil, hyd. etc. heat rejection. It certainly doesn't need any more warming!