Forum: F-16 Design & Construction

TooTall wrote:

It would be 100 gals/bleach to 1 gallon of water will neutralize 1 gallon of H-70. NEVER add straight bleach to H-70. Always dilute it with water first then the bleach. You can also use HTH, but I have never used it. Does it take 100 gallons of bleach to neutralize it, no. I've used about 1/2 of that and it worked great...

What is the contents of the H-70 tank?

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Did you mean capacity? If so, I believe it is around 6.6 gallons.

I want to thank everybody, on the forum "the EPU, how does it work and why Hadrazine?", for their assistance in my PWP-Presentation.

Thanks guys.

Great Site, F-16.net!!!

WOW! Never thought something like the EPU could elicit a 5-page thread! Go fig.

LinkF-16SimDude, I didn't think so either. I just kept reading about the "EPU" and hydrazine and I had no clue as to what and or how or anything! I'd always heard about the ram air turbines and such that used airflow to generate auxiliary power if the engine quit. After reading all the responses (thanks everyone Very Happy

) I finally understand.

Rodney, I'm glad we could help and I'm glad you like this site Cool

. I hope to see you around in the future!

Hydrazine combust under pressure like a diesel engine, the max exposure limit was 2 PPM when I was in the AF at Hahn ab, the amount that you can smell is 3 PPM and It smells like ammonia. Effects on the body they told use that they don't know as for long term..

Hydrazine is really rocket fuel develop in the early 1900's for rockets and still being used in space since it does not need O2.

After a flight one other way to know if the EPU was fired with H-70 is to look at the panel next to the safety pin and look for that disk thru the window, if it is orange its good, if it is purple, it has bin fired.

Run time on the H-70 tank is about 10 to 15 min and there is NO Shrader valve on the unit meaning ground crew does not service it. The EPU powers only a limit amout of electricity for the fly-by-wire, no hydraulics. its not ment to take you home just enough to allow you to land it.
I know this because I was a crew chief in the AF and my A/C was 81-0721 with the stress tape recorder (must change every 10 flt hr) and 84-1303

ximeno wrote:

Hydrazine combust under pressure like a diesel engine, the max exposure limit was 2 PPM when I was in the AF at Hahn ab, the amount that you can smell is 3 PPM and It smells like ammonia. Effects on the body they told use that they don't know as for long term..

Hydrazine is really rocket fuel develop in the early 1900's for rockets and still being used in space since it does not need O2.

After a flight one other way to know if the EPU was fired with H-70 is to look at the panel next to the safety pin and look for that disk thru the window, if it is orange its good, if it is purple, it has bin fired.

Run time on the H-70 tank is about 10 to 15 min and there is NO Shrader valve on the unit meaning ground crew does not service it. The EPU powers only a limit amout of electricity for the fly-by-wire, no hydraulics. its not ment to take you home just enough to allow you to land it.
I know this because I was a crew chief in the AF and my A/C was 81-0721 with the stress tape recorder (must change every 10 flt hr) and 84-1303

Just a couple of small errors you stated about the EPU that I would like to point out. The EPU does provide hydraulic pressure to A system at 2,000 psi. Also, run time of the EPU depends on the state of the engine. If it is running, the EPU can last up to 6 hours because it is in Augment mode, using mostly bleed air to keep the turbine spun up, then Hydrazine if the speed detector sees a drop in RPM. If the engine is not running, then yes...the EPU will only last 10-15 minutes. Keep in mind, the EPU will only automatically fire if one or more of these items happen: 1) Main (A,B models) and Standby (C & D Models) Generators fall off line and/or 2) BOTH hydraulic systems fail. Some mistake that a BATT failure is automatic, when it is not because it is in the pilot's checklist to fire it manually.

Hey you guys, as an old crew dog who's forgotten everything on the EPU in his Block 10 B model, you sure have brought back some memories, thanks.

One of the greater concerns with H70 is its reaction to organic products. The Luftwaffe used H70 in the ME-163 rocket powered aircraft. Wings ran a show on it and showed some training footage on what happened when it contacted some rags - burst into flames within seconds. A number of pilots were burned due to inflight leaks and they wore special protective flight suits. That's one reason why hydrazine response crews wear special gear. And it's also why we are told on the flightline that if the system dumps liquid on us we are to strip off all clothing (naked) and get to the emergency shower. Most maintainers don't know that they will burst into flames if there is a liquid vent on their uniforms.

Dave

Nowadays 'they' are saying the exhaust from hydrazine ins't as dangerous as initally thought, since it degenerates to ammonia and water as someone else mentioned. Ammonia is still hazerdous, but not nearly as much as hydrazine (I worked with ammonia all the time as fertalizer back on the farm, no third arm or purple poops yet). But still, if you are a pilot and want to lose all respect and consideration from your ground crew, let the EPU fire on your CC. Then shut down, bound out of the airplane, and bitch out the CC for trying split and get to the hospital instead of rushing to get your spare ready. Top that off by bitching at the expeditor for trying to rush the CC to the hospital instead of rushing to prep your spare. This wasn't in the desert, where there was a real world mission, mind you- they were going up for a local orientation ride. Important, sure, but not worth jeopordizing the safety of the ground crew in my opinion.

84-1317 got me today when I pulled the pin during the launch. WTF

USAF F-16C block 25 #84-1317 of the 113th TFS has '181TFG' titles on the tail showing its the wing commanders bird.

TooTall wrote:

Did you mean capacity? If so, I believe it is around 6.6 gallons.

Pretty close - 6.7 gal/56 pounds capacity

Also, exposure limits are much lower now that more is known about Hydrazine.

0.10 PPM safe exposure limit, according to the GS

Pressure to A system is still 3000 psi, but flow rate is reduced by about half

[quote="260chief"]84-1317 got me today when I pulled the pin during the launch.quote]

I was called out to a RED-BALL for a flight control problem on a Block 15.

A lot of times the problem could be fixed on the analog FLC system by cycling the MAIN PWR switch, so I had the pilot cycle the switch. Unfortunately he had already done his End of Runway checklist and "armed" his EPU and the pin had already been pulled.

The airplane did exactly what it was supposed to do, loss of main power....EPU fires.....after realizing what happened he taxied the aircraft away to a safe area and the fuel guys got to "clean" the airpalne.

As for me......I got to have a nice heart to heart discussion with our DCM, luckily I was "just a dumb two-striper" at the time. The pilot later told me he got pretty much the same speech, for not waiting until EOR to arm the EPU.

That's one of the main design faults of the F-16A's. At least the Engineers alleviated the EPU activations due to main power loss, with the advent of the 10 KVA Standby generator on all C/D Models.

Still, guys get hosed every now and then.

Mike V

If you smell or sense hydrazine:Water water water water!!!!!!!! Beer

Forum: F-16 Design & Construction

The EPU - how does it work and why hydrazine?