C-130J CAUTION "ENG 2 FUEL PRESS LOW" - BETTER GRAVITY OR ALTERNATE X-FEED?

[sandro.oberoi]

Good morning everyone,

When a main tank boost (for example n°2) pump stops working (no leak and pressure switch tells the truth), the EMG CHKLIST tells us to "use alternate fuel management for cross feed".

Right... so far so good... we prime the manifold and start crossfeeding the engine with the TK2 transfer pump.

But what to do before landing? the manual in section 2D tells us to go tank to engine during landings (except for touch and goes that can be done in crossfeed from aux and ext tanks). Some pilots in my Airbase says that since we are not in a standard situation, we have to disregard section 2 and instead we HAVE TO land with engine 2 still cross feeded by TK2 transfer pump.

In my opinion, it is instead better to land in tank to engine (eng2 feeded by gravity) rather than in Crossfeed from tank 2 since the transfer pump does not suck fuel from the bottom of the tank and during ground roll in reverse i believe it is possible to experience a flame out due to fuel sloshing!

The manual is not clear enough to remove this doubt and I would like to get an aswer from some maitenance expert or test pilot to understand what is better to do during landing... CROSSFEED FROM MAIN TANK or GRAVITY?

Thank you for your attention

Sandro

[NATOPS1]

Land with the engine on crossfeed... This will prevent the flame out not induce it.

There is NO fuel "slushing" (sloshing) because the fuel pump is inside a surge box. The box is full of fuel at all times and remains full due to inward flow as well as fuel pump discharge (water removal system) also the box will not allow the fuel to "leave" the box unless there is too much fuel or the fuel is pumped out by the pump.

[sandro.oberoi]

NATOPS1 i think you did not get my question. You gave a beautiful explanation about the Main tanks Boost Pumps... which of course have a suge box, have a water removal system and prevents flame out etc... and when it works we are in normal operation (not cross feed) ... but before answering to a thread i suggest to read the question...

THE BOOST PUMP HAS FAILED.... we are now force to decide to go for cross feed or gravity.... crossfeeding from its own tank can be done only from its transfer pump.. which is OUT OF THE SURGE BOX... and placed aloft from the bottom of the tank in order to leave a certain amount of fuel in case of dumping... and all is fine as long as we have more than about 1600 pounds of fuel and we do not have to land... when we have to land... we have fuel slosh, that's why the manual says that we can perform touch and goes in cross feed using AUX and EXT tanks (since their transfer pumps are placed on the tank floor... as the main tanks boost pumps are...).

Anyhow...I'm looking for an answer.. not to give one...

Thanks anyway for at least trying...

[SEFEGeorge]

I think you're creating your own confusion. A failed main boost pump is not a standard operating situation. Therefore I would land on crossfeed. With a regular Herc without inflight refueling, etc., there's no in tank pump to fall back on. Never had a failed main tank boost pump. But I would land on crossfeed to ensure that the engine had a constant flow of fuel. On approaches, landings, etc., there's always a chance for a missed approach, tower initiated go around, etc., and I want to make sure that the engine would not flameout from fuel starvation if there was any chance any yanking and banking happening.

[sandro.oberoi]

that's a good point.. u would land using the tank 2 transfer pump because u want fuel to feed the engine on pressure in case of go around etc... good point... but let me go further with what the manual says:

-"FEEDING ENGINE WITH MAIN TANK TRANSFER PUMP" - ....omissis...."perform the following whenever gravity feed is non practical or desided"

-FUEL GRAVITY FEED FOR INFLIGHT OPERATIONS - The ENG 1 (2,3, or 4) FUEL PRESS LO © message can be expected during gravity feed operations. engine operation is normal"

-"cross feed operation for approach and a series of touch and go landings is permitted using fuel from AUX, EXT or fuselage tank..." guess what.. these tanks have transfer pumps placed on the bottom (no big sloshing problems except in case of full stop landing when fuel moves forward and stays there until braking action and reverse are completed)

-"MAIN FUEL TANKS"... omissis... "the transfer pump location ensures a protected amount of fuel that cannot be transfered or dumped " (1520 lbs in level flight)

So, considering in normal ops we can do touch and goes crossfeeding only from AUX and EXT, but we cannot perform full stop landings... what about performing full stop landing crossfeeding from a main tank which transfer pump is placed in order to leave 1520 lbs of fuel not dumpable/transdered in flight... do we know till what amount of fuel, transfer is granted in a brake + reverse sloshing condition? (1520 is not considering landing sloshing).

Thank you for your patience

[NATOPS1]

A few points.

1. Crossfeed is using fuel from any tank to any engine.

2. I would further say that "Crossfeed" is generally defined and accepted as the practice of utilizing the crossfeed manifold and Main Tank Boost Pumps and or the Aux/Ext pumps; NOT the transfer pump, transfer manifold and the Crossfeed manifold.

3. I see your Transfer pump use and would ask why would you use the transfer pump and not the No1 main tank Boost Pump "on crossfeed for landing? (or AUX/EXT)

4. Does your book have a Caution about unbalanced fuel due to the use of transfer pumps and crossfeed?

5. Also if you can do touch and Go "Landings" on crossfeed from the Aux/Ext you can "land" on crossfeed and I would think you could "ABORT" the GO part of a "Touch and GO" Landing yes?

SO to answer your question;

I would NOT land on “crossfeed†from the transfer pump.

I would utilize the main tank Boost pump on that wing; in your example I would use the TK1 Main Tank Boost pump and crossfeed to Engine 2.

Also the Ext tank pumps are located inside a "surge box" so no sloshing...

[sandro.oberoi]

NATOPS1... I thought you did not understand my question perviously.. but actually it was me not getting your answer.. I apologize

your point number 1 and 2 are right.

i agree with your point 3 and some of my colleagues don't.

for the point 4 we do have unbalance limits as any 130 utilizer but it's not an issue in this case

5. normal landings are to be done in tank to engine configuration, touch and goes are exeptions and can be done in xfeed from AUX/EXT or fuselage tank (KC version). your point about abort in the GO part is right.. but i think it includes some risks that's why the pilot is requested not to plan full stops in that configuration.

Your point on landing in cross feed from boost pump of TK1 is a very good point that i did not think about, and I thank you for your advice.

The problem is that the manual does not include any procedure of crossfeeding from other boost pumps (except for the LOW FUEL STATE OPS) and legally i cannot deviate from the manual procedures.

So the 2 options I have are still:

1. Landing in cross feed from TK2 transfer pump (which i don't like because i'm afraid of possible AIR BUBBLE being pushed into the engine due to sloshing

2.Landing in tank to engine configuration (with eng 2 gravity feeded) which i prefer because manual does not give any caution about this.

But still the manual gives wide spaces to own interpretation whether to land in config 1 or 2 and i would like to know how probable it is to experience a flame out by landing with engine crossfeeded with a main tank transfer pump (which does not suck fuel in level flight below 1520 lbs in that tank)

Thank u NATOPS :)

[NATOPS1]

I think I missed the point of your question or at least parts of it also so bad on me as well...

Well given your options...

Depending on fuel level I would land on crossfeed from the transfer pump 4K cutoff (maybe) the pump is more centered in the tank so the fuel would move towards it to some degree.

At lower fuel levels the tank to engine would be better as the fuel pick up is in the surge box and would be more protected.

I would "utilize crossfeed operations" but it would be from #1 boostpump but that’s just me.

I think once you have an "abnormal" situation the "Normal" direction provided becomes secondary and your knowledge becomes primary.

I would think the section that tells you to go tank to engine for landing is based on a boost pump being in an operable condition; it does not have a "boost pump inop" condition exception but that condition IN MY OPINION exempts you from the requirement to comply with a "normal procedure"...