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Date: Mon, 29 May 2006 16:42:00 -0400
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From: Charlie Kohler <charliekohler@yahoo.com>
Reply-To: Charlie Kohler <charliekohler@yahoo.com>
Subject: Re: [LML] Re: How Not to Do 1st Runup
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Just this morning I was able to open the video file of "How Not to Do the First Engine Run".
It reminds me of two Lancair IV scenarios. And I'm sure there are more
.
Scenario one. You are at Oshkosh (Or Sun and Fun). You've been there three or four days. Your LIV has been parked in an area sand in your fuel tanks were nearly full. You come out ready to leave and you notice that you are nearly up to the axle in soft sand.
Knowing that you cannot power out --you except a offer of help from the Air Operations people with a pickup truck to pull it out. Several people on each wing and the pickup truck hooked up to your tow bar, you begin the tow. As it begins to move, you see the right gear fold under. It probably will break two blades of that new MT propeller or worse yet (more expensive) --bend two blades of your new Hartzell Scimitar.
Scenario two. You are in flight and you notice your hydraulic pump light on. After you check gear and flap controls for neutral or off, you decide it's time to stop the pump. You pull the circuit breaker for the hydraulic pump. You follow the emergency gear extension procedure and put the flaps to 10 using the accumulator pressure. It seemed like it took more than the 15/20 and pump's to get the gear down and the handle never did get hard. But at least we have three greens. Your home airport is 3000 feet and you say "if I have to work on it, I want to be a my own hangar with my own tools". With 10 flaps you fly a final approach speed of 100 kn. You eat up 500/1000 feet before you touch down. Now you've really got to get on the brakes. As soon as you hit them hard you feel a slight rise on the right side and then the right wing drops to the pavement and you begin a ground loop spin.
What is common thread through these two imaginary events? No hydraulic pressure to hold the gear in the down position--piston fully retracted (aft) -- and the lock engaged. Without full hydraulic pressure can the lock snap off or out the of the groove? You bet! 
How can you prevent this? For the towing job, it would be better to tow it backwards out of the hole with ropes tied to the main landing gear legs at the tires. (Not on the caliper!) If you have several people with strong backs, have them get underneath the wing and lift up and fill the hole. Always, always turn on the master switch to bring hydraulic pressure up to normal when moving the airplane on any surface.
For the in-flight loss of hydraulic pressure, always choose the longest runway available, hold the nose off as long as possible and use as little brake pressure as possible.

 
Charlie K. 


----- Original Message ----
From: bob mackey <n103md@yahoo.com>
To: Lancair Mailing List <lml@lancaironline.net>
Sent: Saturday, May 27, 2006 11:13:19 PM
Subject: [LML] Re: How Not to Do 1st Runup

If the gear locks fail when pushed by hand, or by thrust from the prop, 
then they will fail just as easily when using the brakes on the runway.

Braking should be able to generate a force aft at the tire about 
equal the weight on the tire. Call if half the gross weight. Usual 
design practices call for 3G loads on the landing gear. If that vertical
load is to be applied while also using maximum braking, then 
each gear leg should therefore be able to take an aft load of at 
least 1.5 times the gross weight: 

(3550 lbs/1G) * 3(G) /  2  (wheels/main gear)  = 5325 lbs. 

I doubt that any of the engine/prop combinations for the Lancair 4
generate over 5000 lbs of thrust, so it would appear that either the 
landing gear in the video was faulty or poorly designed (or both). 

That's not to say that that the test crew in the video didn't make other 
mistakes like forgetting to tie the airplane to the ground or check to 
see if the landing gear was functional. 


Be a chatter box. Enjoy free PC-to-PC calls with Yahoo! Messenger with Voice.
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<P>Just this morning I was able to open the video file of "How Not to Do the First Engine Run".</P>
<P>It reminds me of two Lancair IV scenarios. And I'm sure there are more</P>
<P>.</P>
<P>Scenario one. You are at Oshkosh (Or Sun and Fun). You've been there three or four days. Your LIV has been parked in an area sand in your fuel tanks were nearly full. You come out ready to leave and you notice that you are nearly up to the axle in soft sand.</P>
<P>Knowing that you cannot power out --you except a offer of help from the Air Operations people with a pickup truck to pull it out. Several people on each wing and the pickup truck hooked up to your tow bar, you begin the tow. As it begins to move, you see the right gear fold under. It probably will break two blades of that new MT propeller or worse yet (more expensive) --bend two blades of your new Hartzell Scimitar.</P>
<P>Scenario two. You are in flight and you notice your hydraulic pump light on. After you check gear and flap controls for neutral or off, you decide it's time to stop the pump. You pull the circuit breaker for the hydraulic pump. You follow the emergency gear extension procedure and put the flaps to 10 using the accumulator pressure. It seemed like it took more than the 15/20 and pump's to get the gear down and the handle never did get hard. But at least we have three greens. Your home airport is 3000 feet and you say "if I have to work on it, I want to be a my own hangar with my own tools". With 10 flaps you fly a final approach speed of 100 kn. You eat up 500/1000 feet before you touch down. Now you've really got to get on the brakes. As soon as you hit them hard you feel a slight rise on the right side and then the right wing drops to the pavement and you begin a ground loop spin.</P>
<P>What is common thread through these two imaginary events? No hydraulic pressure to hold the gear in the down position--piston fully retracted (aft) -- and the lock engaged. Without full hydraulic pressure can the lock snap off or out the of the groove? You bet! </P>
<P>How can you prevent this? For the towing job, it would be better to tow it backwards out of the hole with ropes tied to the main landing gear legs at the tires. (Not on the caliper!) If you have several people with strong backs, have them get underneath the wing and lift up and fill the hole. <U>Always, always</U> turn on the master switch to bring hydraulic pressure up to normal when moving the airplane on any surface.</P>
<P>For the in-flight loss of hydraulic pressure, always choose the longest runway available, hold the nose off as long as possible and use as little brake pressure as possible.</P></FONT><BR>&nbsp;</DIV>Charlie K.
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">
<DIV><BR><BR>----- Original Message ----<BR>From: bob mackey &lt;n103md@yahoo.com&gt;<BR>To: Lancair Mailing List &lt;lml@lancaironline.net&gt;<BR>Sent: Saturday, May 27, 2006 11:13:19 PM<BR>Subject: [LML] Re: How Not to Do 1st Runup<BR><BR>If the gear locks fail when pushed by hand, or by thrust from the prop, <BR>then they will fail just as easily when using the brakes on the runway.<BR><BR>Braking should be able to generate a force aft at the tire about <BR>equal the weight on the tire. Call if half the gross weight. Usual <BR>design practices call for 3G loads on the landing gear. If that vertical<BR>load is to be applied while also using maximum braking, then <BR>each gear leg should therefore be able to take an aft load of at <BR>least 1.5 times the gross weight: <BR><BR>(3550 lbs/1G) * 3(G) /&nbsp; 2&nbsp; (wheels/main gear)&nbsp; = 5325 lbs. <BR><BR>I doubt that any of the engine/prop combinations for the Lancair 4<BR>generate over 5000 lbs of thrust, so it would
 appear that either the <BR>landing gear in the video was faulty or poorly designed (or both). <BR><BR>That's not to say that that the test crew in the video didn't make other <BR>mistakes like forgetting to tie the airplane to the ground or check to <BR>see if the landing gear was functional. <BR><BR><BR>
<P>
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