Start 2 anyone?

Operating an F-16 on the ground or in the air - from the engine start sequence, over replacing a wing, to aerial refueling procedures
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VarkVet

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Unread post14 Jan 2011, 22:23

Why did we go to start 2 when the F-16 will start flawless in start 1?
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Davis83

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Unread post14 Jan 2011, 22:39

Waiting on an Ops person to answer fully, but i think it had to do with a change in their manual. I never used it when doing an engine run - always used start 1. Like you said it worked flawlessly. I think their manual changed when we went from JP-4 to JP-5.

I heard someone say that start 2 had twice the power? uh 3000psi + 3000psi = 3000psi - you have twice the volume, but same pressure.
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rpgrynn

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Unread post14 Jan 2011, 22:42

cuz 2 provides 40% more power with both bottles to the JFS hydraulic start motor. This provides a much cleaner start of the JFS. The history books had us use 2 only for adverse conditions (Too Hot or Cold, high altitudes)..That’s the very short of it! :)
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Unread post14 Jan 2011, 22:46

rpgrynn wrote:cuz 2 provides 40% more power with both bottles to the JFS hydraulic start motor. This provides a much cleaner start of the JFS. The history books had us use 2 only for adverse conditions (Too Hot or Cold, high altitudes)..That’s the very short of it! :)


OK ... so why do we motor a Pratt for 1 minute, even first start of the day?
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rpgrynn

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Unread post14 Jan 2011, 23:12

LOL 220 only - to check for fuel fog to avoid hot starting -- Next? :)
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Unread post14 Jan 2011, 23:45

rpgrynn wrote:LOL 220 only - to check for fuel fog to avoid hot starting -- Next? :)


680 max for a pratt and 935 for GE for start FTIT, never seen anyting near a hot start in a Viver?

Fog is BS ... seen it 2 times in 8 years, never lit off, so non player
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exfltsafety

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Unread post14 Jan 2011, 23:47

I think Davis83 is right. The flight manual was changed to build a consistent pilot habit pattern of start 2 use so that when the JFS was needed for an airstart, start 2 would be selected. Prior to the change, at least one pilot erred and selected start 1, realized the error and immediately tried to correct it by going to start 2, causing the start to fail. At least that's my recollection.

Added later: I had second thoughts after posting the above. I think there was also a time when JFS start reliability on the ground wasn't great. Changing to start 2 use helped that problem and also provided the consistent pilot habit pattern I mentioned.
Last edited by exfltsafety on 14 Jan 2011, 23:57, edited 1 time in total.
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That_Engine_Guy

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Unread post14 Jan 2011, 23:50

rpgrynn wrote:LOL 220 only - to check for fuel fog to avoid hot starting -- Next? :)


Not fuel fog, but 'bowed rotor'

The 1 minute motor WAS for only second starts of the day, or it the engine was warm. People were screwing it up so bad, they made it EVERY start.

Quickly; when a PW-220 sits after being run, the heat in the engine naturally migrates to the top portion of the engine. This keeps the top half hot, while the bottom half cools. The N2's rotor design then warps or looses it's straight/round shape. If you start the engine and let it achieve idle before the temperature of the rotor is evenly normalized, it will allow the compressor blades to dig into the seals around the N2 rotor blades. This increases tip/seal clearances, and over time will result in compressor stalls during take-offs, more in hot weather when the compressor is working hard.

Tinker actually did a great movie/presentation of the whole process; great computer graphics and explanations. I doubt may 'new' people have seen it since they made the "motor to cool" changes long ago.

FYI- the PW-229 has a different, stiffer rotor design that doesn't 'bow' under the same conditions. You also don't scavenge the oil system of the PW-229

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Unread post15 Jan 2011, 00:08

If your sh*t don't start in "1" fix it ... that was the initial plan?
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That_Engine_Guy

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Unread post15 Jan 2011, 00:31

That's the way it should be, but obviously the USAF has other concerns for our young airmen versus their maintenance skills, pride in their jet or mind-set.

These days the USAF is about new uniforms every 3 years, private rooms, chow-hall vouchers and PT scores. :doh:

Come on Vark, you should know that!?!

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rpgrynn

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Unread post15 Jan 2011, 01:11

TEG - Thanks!! just a little rusty.
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Weasel_Keeper

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Unread post15 Jan 2011, 07:34

VarkVet wrote:If your sh*t don't start in "1" fix it ... that was the initial plan?


But you're allowed two attempts at a start before ground abort.

What I heard when I asked the question a few years ago about start 2...start 1 doesn't record data but start 2 does.

*shrugs*
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Kreeskid99

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Unread post15 Jan 2011, 07:49

The true story is the acft is setup up to start the CSFDR when Start 2 is enabled. It was changed for this reason, to get actual times of when the aircrew started the aircraft in case of a mishap. In start 1, the CSFDR doesn't start recording until WOW switches are disengaged (or engaged, on how you perceive the system).
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JoeSambor

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Unread post15 Jan 2011, 07:54

Nope. CSFDR starts recording when the throttle comes out of idle. Tell 'em, Larry.

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Weasel_Keeper

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Unread post15 Jan 2011, 08:05

Kreeskid99 wrote:The true story is the acft is setup up to start the CSFDR when Start 2 is enabled. It was changed for this reason, to get actual times of when the aircrew started the aircraft in case of a mishap. In start 1, the CSFDR doesn't start recording until WOW switches are disengaged (or engaged, on how you perceive the system).


This is what I was trying to say but I couldn't remember the name...lol. :) I'm an A-10 guy now so we always go start 1...to start the #1 engine...heh.
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