Fuel leakage during in-flight refueling

[mark johnston]

When refueling using the probe and drogue system, is it commonplace to have
fuel leakage from the drogue? At my day job, we have a foreign customer
asking about the resistance of an engine to fuel ingestion during refueling.
Apparently it is something of a problem for them, but they have not been
able to give us any specifics.

I thought someone here may have some real world experience they could share.
Do you get a brief mist of fuel when you disconnect? ... or can you
experience an continual "dribble" down the probe during the transfer? Any
info or war stories would be helpful.

Regards,

Mark Johnston

[[email protected]]

As far as I saw this on a sort of film that is a mist, indeed. Bear in
mind the fact that in many planes the refueling probe is often quite
distant from the jet intake.

Any dumped fuel seemingly turns into mist as well.

One story I've heard from civil aviation: it happened probably in
France in the 1980s, when a passenger jet exploded after unluckily
coming into the cloud of fuel it dumped one lap before.

In Britain in WWII there was a weird idea to spray fuel in the air, to
make V-1 missile engines suck it, fly longer than expected, and then
overfly their targets.

Best regards,

Jacek

[Phormer Phighter Phlyer]

mark johnston wrote:
> When refueling using the probe and drogue system, is it commonplace to have
> fuel leakage from the drogue? At my day job, we have a foreign customer
> asking about the resistance of an engine to fuel ingestion during refueling.
> Apparently it is something of a problem for them, but they have not been
> able to give us any specifics.
>
> I thought someone here may have some real world experience they could share.
> Do you get a brief mist of fuel when you disconnect? ... or can you
> experience an continual "dribble" down the probe during the transfer? Any
> info or war stories would be helpful.
>
> Regards,
>
> Mark Johnston
>
>
>

May get a wee bit when you pull out but no leakage when refueling.

[John]

I am stretching here, but I seem to recall this is the reason that the
AAR probe on the A-4 Skyhawk was revised from a straight design to one
that incorporated a "dog leg." If I recall correctly, when the
Scooter backed away from the basket, a valve in the end of the probe
would sometimes allow a puff of fuel to escape. In the original
straight design, the puff would then be promptly ingested down the
starboard engine intake. This occasionally would do bad things to the
engine and create a bad day for the pilot. The "dog leg" design
moved the path of the fuel puff far enough away from the inlet to
prevent ingestion.

If I am wrong, I hope someone will correct me on this.

Blue skies . . .

[Ed Rasimus]

On 24 Mar 2005 09:36:13 -0800, "John" > wrote:

>I am stretching here, but I seem to recall this is the reason that the
>AAR probe on the A-4 Skyhawk was revised from a straight design to one
>that incorporated a "dog leg." If I recall correctly, when the
>Scooter backed away from the basket, a valve in the end of the probe
>would sometimes allow a puff of fuel to escape. In the original
>straight design, the puff would then be promptly ingested down the
>starboard engine intake. This occasionally would do bad things to the
>engine and create a bad day for the pilot. The "dog leg" design
>moved the path of the fuel puff far enough away from the inlet to
>prevent ingestion.
>
>If I am wrong, I hope someone will correct me on this.
>
>Blue skies . . .

Never tried to put my broad butt in a Scooter, but other aircraft with
the dog leg in the probe, such as the F-100, did it to move the
refueling point into quieter air out of boundary layer or to improve
pilot visibility for hook up.

The very small amount of fuel that sprayed at disconnect either from a
drogue or off the boom from a receptacle surely wouldn't do much to an
engine under normal conditions. In the F-105, the spray of mist would
fog the windscreen and then blow off in two seconds. Any fuel that
went down the intake could be sniffed in a second or two as it came
through the pressurization system--which is why the checklist for
refueling specified 100% oxygen.

Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[John]

I knew I was on thinning ice, but at least I know that being shot down
by Ed means I have been shot down by one of the better ones.

I just found this at http://www.skyhawk.org/2C/productionhistory.htm
regarding design changes to the A-4F.

"A unique recognition feature that first appeared on the A-4F was the
"bent" aerial fueling probe. The probe was so configured to preclude
electronic inteference with the wide-angle target acquisition
system."

Also found this at http://www.airtoaircombat.com/detail.asp?id=57 :

"The A-4M was fitted with a revised refuelling probe which canted out
to starboard to precent interference with a wider-angle target
acquisition system."

Now that Ed has thrown the thrid strike, it is time for me to head back
to the dug-out and resume lurking. (Smiling)

blue skies . . .

P.S. to Mr Rasimus - Is the new book actually out yet (fingers
crossed)?

[Sparerep]

On 24 Mar 2005 10:18:18 -0800, "John" >
wrote:

>I knew I was on thinning ice, but at least I know that being shot down
>by Ed means I have been shot down by one of the better ones.
>
>I just found this at http://www.skyhawk.org/2C/productionhistory.htm
>regarding design changes to the A-4F.
>
>"A unique recognition feature that first appeared on the A-4F was the
>"bent" aerial fueling probe. The probe was so configured to preclude
>electronic inteference with the wide-angle target acquisition
>system."
>
>Also found this at http://www.airtoaircombat.com/detail.asp?id=57 :
>
>"The A-4M was fitted with a revised refuelling probe which canted out
>to starboard to precent interference with a wider-angle target
>acquisition system."
>
>Now that Ed has thrown the thrid strike, it is time for me to head back
>to the dug-out and resume lurking. (Smiling)
>
>blue skies . . .
>
>P.S. to Mr Rasimus - Is the new book actually out yet (fingers
>crossed)?
>

Don't be too hasty, John.

It is true that the off-set probe was installed as part of
AFC 461, titled Avionics; AN/APS 117 Shrike Target
Identification Acquisition System and it's also true that it
was installed because the straight probe interfered with the
sensor operation.

However, it was also found to prevent fuel vapor
ingestion/explosion when the coupling leaked during
in-flight refueling. A second part to the AFC (Part 2) was
issued a couple of years later to authorize off-set probe
installation on all aircraft not covered under the original
AFC. The part 2 title was changed to Fuselage; Offset IFR
Probe Installation and TIAS, Provisions For. That's why
some TA-4s had the off set probe. The original AFC was for
"designated" A-4Es and Fs.

I remember reading through A-4 accident summaries a few
years ago and it seemed that the USN/USMC lost and average
of a plane a year to fuel vapor ingestion during IFR.

In May 83 NAVAIRSYSCOM message 260109Z, all A-4 aircraft not
equipped with the off-set probe (AFC-461) were restricted
from aerial refueling from KC-135 aircraft equipped with the
boom to drogue adapter with the exception of operational
necessity.

The restriction was in response the loss of a TA-4J due to
the leaking/ingestion problem and several more reports that
it occurred. I don't remember that restriction ever being
lifted.

Tom Debski

[John Weiss]

"John" > wrote...
>I am stretching here, but I seem to recall this is the reason that the
> AAR probe on the A-4 Skyhawk was revised from a straight design to one
> that incorporated a "dog leg." If I recall correctly, when the
.. . .

> If I am wrong, I hope someone will correct me on this.

All too true! In the later years of the Scooter, inflight refueling was
prohibited with the straight probe.

[Doug \Woody\ and Erin Beal]

On 3/24/05 8:24 AM, in article
1111674154.81566ae09bb49e973412b142c168a8e4@terane ws, "Phormer Phighter
Phlyer" > wrote:

> mark johnston wrote:
>> When refueling using the probe and drogue system, is it commonplace to have
>> fuel leakage from the drogue? At my day job, we have a foreign customer
>> asking about the resistance of an engine to fuel ingestion during refueling.
>> Apparently it is something of a problem for them, but they have not been
>> able to give us any specifics.
>>
>> I thought someone here may have some real world experience they could share.
>> Do you get a brief mist of fuel when you disconnect? ... or can you
>> experience an continual "dribble" down the probe during the transfer? Any
>> info or war stories would be helpful.
>>
>> Regards,
>>
>> Mark Johnston
>>
>>
>>
>
> May get a wee bit when you pull out but no leakage when refueling.

I disagree.

About 20% of the time (anecdotally) I've seen leakage from USAF tankers
(KC-135, KC-10 whether on the MIPR, WOPR, or iron maiden) during refueling.
My guess would be due to higher pressure. The puff during back out happens
nearly all the time though on Navy or USAF tankers.

It is VERY uncommon for that leakage to become a problem. Misting fuel will
smudge the canopy a bit though.

There was a Tomcat circa 1997 from VF-211, however, that during a severe
leak from the drogue ended up ingesting quite a bit of fuel down one motor
and landing at NAS Fort Worth. That jet's still at NAS FW, by the way.

--Woody

[Red Rider]

"Doug "Woody" and Erin Beal" > wrote in message
...

snip, snip, snip,
>
> It is VERY uncommon for that leakage to become a problem. Misting fuel
will
> smudge the canopy a bit though.
>
snip, snip, snip,
>
> --Woody
>

Had hydraulics' go bad on launch once. With other things on my mind, I just
dumped excess fuel. Next liberty port I had to avoid a destroyer crew who
wanted to tell me that dumped fuel doesn't just disappear in a mist. They
were lucky I had already dumped the ordnance on them. <grin>

Red

[Ed Rasimus]

On 24 Mar 2005 10:18:18 -0800, "John" > wrote:
>
>Now that Ed has thrown the thrid strike, it is time for me to head back
>to the dug-out and resume lurking. (Smiling)
>
>blue skies . . .
>
>P.S. to Mr Rasimus - Is the new book actually out yet (fingers
>crossed)?

Actually, we don't throw strikes or even brush-backs in the better
newsgroups. We just share knowledge and hopefully get a bit wiser.

As for the book, coincidentally just this week I got a contract offer
from St. Martin's Press and the book which was delayed by the failure
of Smithsonian Books is now back on track.

The book should revert to the original title I had for it which is
"Palace Cobra: Fascination With A War" rather than the previously
announced "Phantom Flights, Bangkok Nights" (Smithsonian imposed, but
it sounded to me like a grade B porno movie.)

Anticipated availability won't be until the end of the year with the
new publisher.

Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[John]

Mr. Rasimus,

It was supposed to be on last Christmas' list. Now I guess I will have
to wait until next Christmas. Sheesh. Congratulations on the
contract.

But please, do explain the term "Palace Cobra"

John

[Ed Rasimus]

On 25 Mar 2005 10:09:33 -0800, "John" > wrote:

>Mr. Rasimus,
>
>It was supposed to be on last Christmas' list. Now I guess I will have
>to wait until next Christmas. Sheesh. Congratulations on the
>contract.
>
>But please, do explain the term "Palace Cobra"
>
>John

"Palace Cobra" was the program name for the AF personnel policy
regarding assignment of aircrews to Southeast Asia. It was the
misguided concept that no one should go a second time until everyone
had gone the first--which led to the idea of the "universally
assignable pilot". Thinking that you can take an "experienced" pilot
out of B-52s, KC-135s, C-124s or Training Command and with sixty hours
make that individual a competent fighter pilot is stupid.

The fact of the matter is that there were lots of tactical aviators
who went to SEA more than once and a lot of folks who successfully
avoided the exposure.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com

[Bob]

I think the probe was "bent" to get the receiver out of the tanker's
wash. Most navy planes with probes had the probe out in front of the
pilot to make it easier to plug in. Some like the Fury had the probe
way out and were a bitch to plug. Crusaders probe was behind the pilot
and made for a few missed plugs. Little fuel leakage, even into the
intake, was no problem. But some guys just weren't happy unless they
could bitch about something. I liked to get the gas no matter some
leaks. Beat punching out all to heck.

[John Weiss]

"Bob" > wrote...
>I think the probe was "bent" to get the receiver out of the tanker's
> wash.

Don't think so...

The A-4 with the straight probe was damn easy to plug -- just stick your
right foot in the basket! It was a whole lot easier than the A-6 with the
big bent probe way up top!

[[email protected]]

Ed brought up Palace Cobra. First, let me say I never evebn saw any
fuel when refuleing with teh F4 (Duh!- the recptacle's about three feet
beind the cockpit). Anyway - I was an RTU IP when this was going on -
we even got an O5 who'd been at Lawrence Livermore Lbs doing nuke
design for the last 10 years to check out in the F4. He was so full of
classified smarts he wasn;t going anywhere and definitely not to SEA.
But that was okay - he couldn't fly the F4 either and we finally gave
up trying to tech him how. . OTH I had a B52 copilot who oved the F4,
flew it like he was born in it and still hade to go back to B52s. TANJ
- there ain't no justice. If there was, USAF DCS/P would be frying in
hell right now. 'Palace Cobra' sent a lot of 'fighter pilots' over to
SEA who were seriously short of fighter skills. On the job training in
combat is not a very smart way to fight a war. But, seriously, it was
fun to sit around the Patrick AFB O Club (Cape Canaveral) and listen to
a lot of Space Command guys wearing wings whining about their
experience being too valuable to be sent off to SEA. Walt BJ