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More left horiZ

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f4ffm2(at)adelphia.net
Guest

Posted: Fri May 11, 2007 1:40 pm Post subject: More left horiZ

Thank guys for your comments.



However, I was  trying to get someone who actually knows what  

happened to CAUSE this particular accident....which did happen in  

Durban, South Africa on April 22nd. It did happen in the run up area  

while involved in some kind of formation activity.



  I thought it would be educational if one of the folks from South  

Africa with FACTUAL FIRST HAND knowledge were to post a debriefing  

here on the list.  Several days ago, I did ask, on the list, if  

anyone from SA could update us on the list about this  

collision...but, so far, no response. This lists main value is its'  

ability to disseminate real world operational information. And this  

might be a prime example of that ability.



We all know that a Yak 52 can be started and, depending on the  

individual airplanes' air system, taxiied for some distance before it  

becomes obvious that one can neither steer nor stop...because the  

main air valve is not on.



I can tell you from personal experience that this is a bit of a  

queezy feeling.  Fortunately, the only thing in front of me was a  

fence which was far enough away that I had time to get the air on and  

turn before "spending a lot of money real fast" or worse.  Some of  

our fellow "listers" have not been so lucky.



So, from the photos....it appears obvious that the dark colored  

airplane's prop did hit the silver airplanes' left horizontal  

stabilizer and elevator.  It appears that only one prop blade may be  

damaged on the dark airplane...leading me to speculate that perhaps  

the pilot of the dark airplane might have switched off his mags after  

discovering that he couldn't stop or steer...but, just a bit too late  

to avoid the silver airplane.



The above paragraph is just speculation, of course.  But it is  

speculation based on an incident that occurred only a year or so ago  

involving our local area formation group...also in the run-up area.   

That incident did not involve any damage, fortunately....but only  

because when the "air off" airplane discovered he couldn't stop or  

steer, he was pointed just enough to the side that he just sort of  

"drifted" past me (and the rest of the formation) with his prop  

stopped and a helpless look on his face.  Fortunately, as he left the  

paved area...he rolled onto quite level ground and coasted to a  

stop....turned the air on, restarted the engine, and rejoined the  

formation a bit the wiser (as were all of us who witnessed to event).



Enough of my what ifs.  South Aftican Yak folks....what happened to  

cause this incident?



Thanks,



Roger

jorgen.nielsen(at)mweb.co
Guest

Posted: Fri May 11, 2007 2:01 pm Post subject: More left horiZ

I will find out and post.



Jorgen



--

viperdoc(at)mindspring.co
Guest

Posted: Fri May 11, 2007 3:35 pm Post subject: More left horiZ

Are we forgetting the last entry in the EP section of the Russian Checklist?

Loss of braking

Mags off.

Doc



--

f4ffm2(at)adelphia.net
Guest

Posted: Fri May 11, 2007 5:18 pm Post subject: More left horiZ

No "Ace", "we're" not forgetting anything.  I thought you Wind Force,  

no that's Air Force...sorry.....guys had more latitude than to  

blindly follow some checklist...I guess not.  In my flying career,  

doc, which includes quite a few airplanes, quite a few hours, quite a  

few years....I always operated with the philosophy of... if something  

goes wrong with my flying machine...and I can fix it immediately  

without endangering anybody outside or any property outside, or  

endangering myself or anybody inside my airplane, or doing any damage  

to my airplane...that I would do that, thereby avoiding having an  

emergency and thus not having to run any flippin' Emergency Checklist.



Anybody that wants to certainly can feel free to sit back in their  

cozy office and offer whatever criticism that they want....but it's  

largely irrelevant.

Roger "Only Posts when it's important or interesting"  

Baker_______________________________________________________________

On May 11, 2007, at 4:32 PM, Roger Kemp M.D. wrote:



[quote] 

 <viperdoc(at)mindspring.com>



 Are we forgetting the last entry in the EP section of the Russian  

 Checklist?

 Loss of braking

 Mags off.

 Doc



 --

jorgen.nielsen(at)mweb.co
Guest

Posted: Sat May 12, 2007 2:24 am Post subject: More left horiZ

OK here goes - just got off the phone with the owner of the Yak that got

chopped up.



The other Yak pilot (that ran into the parked Yak) had a air low problem

before startup.  They then handpropped the aircraft.  There was apparently

enough air to taxi / brake.  During the taxi the air obviously got depleted

faster than it was being replenished, and suddenly brakes did not work, and

she ran into the yak in front.



The mags were not switched off before impact.  The emergency air for

gear/brakes was not deployed.



My analysis:

Contributing factors - low time on the Yak.

Seeming lack of familiarity of the systems.

Formo training environment probably contributed (i.e. looking at other

aircraft instead of keeping a beady eye on the air pressure gauge during

taxi).



This incident could have been avoided if:

1. the pilot had charged the air system on the ground

2. the pilot had waited for air pressure to rise substantially before taxi.

3. the pilot had monitored the air pressure.

4. the pilot deployed emergency air

5. the pilot turned the engine off.



Bottom line.  Know your aircraft and systems, follow the procedures, and do

not get pressured into flying if things are not 100%.



Jorgen  



--

wlannon(at)cablerocket.co
Guest

Posted: Sat May 12, 2007 8:20 am Post subject: More left horiZ

Jorgen;



Very good analysis. If I may I would add one more

to the could have been avoided list. Ground operation of the aircraft is an 

individual task. Formation begins after positioning for takeoff.



Walt



---

Gpw678(at)aol.com
Guest

Posted: Sat May 12, 2007 11:37 am Post subject: More left horiZ

ok, first hand. ( I was there)

  Enough spec, yes all of the above, however, there was a small prob  with the mentioned aircraft.  the main Problem was that the "snot" Valve  was turned (due to a spring malfunction) a further 180 degrees and this then  lead  to a pressure depleation.that then lead to a brake failure.

  

 If you do not know exactly what happened, then please remain quiet untill  you do. You can speculate as much as you like like, but do not become the AAIB  untill you have all the facts!!!

  

 it was unfortunate and was dealt with as best as could in the  situation.

  

 if you can contribute anything constructive, please  let us  know.

  

 thanks

     [quote][b]

jan.mevis(at)informavia.b
Guest

Posted: Sat May 12, 2007 11:48 am Post subject: More left horiZ

Sorry, but I don’t understand how an open snot valve can cause a depletion of the system, unless of course it was already as good as empty ?   

   

Jan Mevis  

RA2005K  

YK50  

         

  

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Gpw678(at)aol.com

 Sent: zaterdag 12 mei 2007 21:37

 To: yak-list(at)matronics.com

 Subject: Re: More left horiZ  

  

     

ok, first hand. ( I was there)  

    

 Enough spec, yes all of the above, however, there was a small prob with the mentioned aircraft.  the main Problem was that the "snot" Valve was turned (due to a spring malfunction) a further 180 degrees and this then lead  to a pressure depleation.that then lead to a brake failure.  

    

   

    

If you do not know exactly what happened, then please remain quiet untill you do. You can speculate as much as you like like, but do not become the AAIB untill you have all the facts!!!  

    

   

    

it was unfortunate and was dealt with as best as could in the situation.  

    

   

    

if you can contribute anything constructive, please  let us know.  

    

   

    

thanks  

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      [quote][b]

viperdoc(at)mindspring.co
Guest

Posted: Sat May 12, 2007 12:33 pm Post subject: More left horiZ

If that is the case, then everytime you opened your snot valve you would deplet the system not just blow off the pressurized oily condensation. You need to look at the check valve proximal to the snot bottle. At least that is the humble opinion of or YAK geru, Dennis Savarese, here in Al.  

Good luck,  

Doc  

         

  

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Gpw678(at)aol.com

 Sent: Saturday, May 12, 2007 2:37 PM

 To: yak-list(at)matronics.com

 Subject: Re: More left horiZ  

  

     

ok, first hand. ( I was there)  

    

 Enough spec, yes all of the above, however, there was a small prob with the mentioned aircraft.  the main Problem was that the "snot" Valve was turned (due to a spring malfunction) a further 180 degrees and this then lead  to a pressure depleation.that then lead to a brake failure.  

    

   

    

If you do not know exactly what happened, then please remain quiet untill you do. You can speculate as much as you like like, but do not become the AAIB untill you have all the facts!!!  

    

   

    

it was unfortunate and was dealt with as best as could in the situation.  

    

   

    

if you can contribute anything constructive, please  let us know.  

    

   

    

thanks  

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        [quote][b]

dsavarese(at)elmore.rr.co
Guest

Posted: Sat May 12, 2007 12:34 pm Post subject: More left horiZ

If the snot valve was open AND the system leaked down, the problem is  not with the snot valve being left open.  The problem is the  check valve closest to the snot valve on the firewall has failed.  If the  aforementioned check valve has failed, opening the snot valve or leaving  the snot valve open due to a failed spring will deplete the air in the main  air tank.  The system will never leak down if the aforementioned check  valve is working properly even if the snot valve is left open.   Leaving the snot valve open with the engine running will prevent the main air  system from recharging.

 Dennis

  

  

   

 [quote]   ---

cjpilot710(at)aol.com
Guest

Posted: Sat May 12, 2007 7:35 pm Post subject: More left horiZ

In a message dated 5/12/2007 4:35:17 P.M. Eastern Daylight Time,  dsavarese(at)elmore.rr.com writes:

  

  

 Dennis is correct, if the snot valve happens to remain open, the system can  not recharge.  The check valve down stream can be perfectly good and hold  pressure.  However, if the pilot is using normal brake applications, that  alone will deplete the system pressure.  Each time you release the brake  handle, you release pressure from the system.  If the system starts out  low, it won't take long to be down to nothing.  I seem to remember reading  somewhere the minimum air pressure for brakes was 10 atoms.

  

 It is a good idea to always take note of your air pressure right after  starting.  You should see some rise (not a lot) on gage before you start to  taxi.  Make sure you're making pressure.  If you start out with low  pressure, you simply must monitor your pressure closely and be ready mentally to  hit the mag switch off and open emergency air.  Remember the compressor  does NOT recover the pressure in the system very quickly and using the  brakes a lot, can draw down the pressure in the system even if every thing  is tight.

  

 Jim "Pappy" Goolsby

  

  

  

  

 [quote]   If the snot valve was open AND the system leaked down, the    problem is not with the snot valve being left open.  The    problem is the check valve closest to the snot valve on the firewall has    failed.  If the aforementioned check valve has failed, opening the    snot valve or leaving the snot valve open due to a failed    spring will deplete the air in the main air tank.  The system will    never leak down if the aforementioned check valve is working properly    even if the snot valve is left open.  Leaving the snot valve open    with the engine running will prevent the main air system from  recharging.

   Dennis

    

    

   

   [quote]     ---

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