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Nose gear bungees

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grs-pms(at)comcast.net
Guest

Posted: Sun Oct 08, 2006 12:04 pm Post subject: Nose gear bungees

Could the deterioration of the nose gear bungees be  related to heat under the cowl?  Particularly in installations where the  muffler is close to the bottom of the bungee?  Anyone try to shield the  bungee from radiated heat?

  

 George

  

 Do not archive

  

   [quote][b]

mfothergill(at)sympatico.
Guest

Posted: Sun Oct 08, 2006 2:42 pm Post subject: Nose gear bungees

Hi;

The nose gear is subject to wear due to rotation for steering, both in 

the air and on the ground. It is also bounced more. Make sure that you 

smooth out the welds where the bungee passes around the 3/4" tubes.

Mike

UHS Spinners



George Swinford wrote:

 	  Quote: 	
		   Could the deterioration of the nose gear bungees be related to heat 

 under the cowl?  Particularly in installations where the muffler is 

 close to the bottom of the bungee?  Anyone try to shield the bungee from 

 radiated heat?

  

 George

  

 Do not archive

peterd(at)metec.co.nz
Guest

Posted: Sun Oct 08, 2006 5:46 pm Post subject: Nose gear bungees

Hi George,

 I did make up a heat shield (see attached image) to  deal with the issue of radiated and circulated heat after engine shut-down.  FWIW, I have yet to prove any benefit, but it was simple to do at the  time.

  

 Tail winds

  

 Peter Dunning

 CH601HD/6-3884/912S

 [quote]   ---

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xl(at)prosody.org
Guest

Posted: Sun Oct 08, 2006 10:02 pm Post subject: Nose gear bungees

I just replaced my nose gear bungee at 400 hours.

The outer cover was frayed and some of the rubber

bands were cut. I ordered the new 1080 bungee from

Zenith. It wasn't clear to me which one to order from

Aircraft Spruce, so I went with the 'safe one'.

The new bungee must be about 1" longer because now

I have about a 1/2" gap at the top of the steel plate.

I had no gap before the replacement. The bungee is

about the same diameter and it works so I'll go with it.



I have no heat shield and the old bungee did not look

like it was affected adversely by the engine + exhaust heat.



I tried the bungee replacement tool sold by Travis, of

Kobush Welding and Machining, LLC. It did not work for

me. It could not get a grip under the bungee and it did damage

the old bungee when I tried to use the tool to remove the

bungee. I was reluctant to use it to install the new bungee.

I found that I didn't need it anyway. And the instructions

were poor. For example, no mention of having to remove the gear

to drop it enough to remove the old bungee. Yes, that is obvious,

so why isn't it in the instructions?? I sent an email to

Travus a week ago telling him that the tool did not work for

me and asking him if I could return it. I did not get a reply

yet.....



To get the front gear back in place I used a rachet strap

around the front gear and the main gear. I let gravity

do the work of compressing the bungee.



BTW, I use two 60 pound sand bags on the elevator to lift

the nose when I need to work on the front gear.

These are the same sand bags I used to put 240 pounds in

the passenger seat for gross weight flight testing.

The couple of dollars/bag weren't wasted.



Joe E

N633Z (at) BFI

CH601XL, 400 hours (677 hours to go before flight time = build time)

Jabiru 3300, Sensenich 49x64 wood prop

klaus(at)utdallas.edu
Guest

Posted: Mon Oct 09, 2006 10:56 am Post subject: Nose gear bungees

Hi,



The nose gear bungees seem to fail because of the small diameter of the

four tubes where the bungee makes an almost-180 deg turn. In my case, the

muffler is in the area of the bungee, but twice the failure came from 

fraying

at one of the tubes. A simple fix of the small-diameter problem does not

seem possible, and replacing the bungee every 500 hours may be the

most convenient solution.



The use of sandbags on the horizontal stabilizer to lift the nose gear 

is not

such a good idea. One might argue that this okay since the horizontal

stabilizer/elevator must lift the nose gear on takeoff. But

when the plane rotates on takeoff, the wings already

carry almost all of the weight of

the airplane. Thus, the horizontal stabilizer/elevator force

needed for rotation on takeoff is much, much

smaller than the force needed to lift the nose gear while parked.

Cessna some years ago had failures of the horizontal stabilizer

spar of the 152 because people would push down on the elevevator to lift

the nose gear when parking the plane in a tight spot.



Best wishes,



Klaus Truemper



-- 

Klaus Truemper

Professor Emeritus of Computer Science

University of Texas at Dallas

Erik Jonsson School of Engineering and

  Computer Science EC31

P.O. Box 830688

Richardson, TX 75083-0688

(972) 883-2712

klaus(at)utdallas.edu

www.utdallas.edu/~klaus

xl(at)prosody.org
Guest

Posted: Mon Oct 09, 2006 9:32 pm Post subject: Nose gear bungees

I don't want to win a Darwin award - save me from that.



I place the sandbags at the root of the elevator, not at the outboard

ends. I will not use the sandbags if it will cause damage. I obviously,

don't think that placing 120 pounds of sand on the root of the elevator

will damage the elevator. I want to know if I'm wrong. Two G steep turns

must place more than 120 pounds of apparent weight on the elevator. I

agree that in flight the CG is forward of the landing gear and less force

is needed to lift the nose. But, on takeoff I tend to pull to lift the nose,

the 601XL is nose heavy, and that must take about the same force as

lifting the nose at rest - the wheels are still on the ground. The

'weight' on the elevator needed to rotate the nose during takeoff must be

close to 120 pounds. The wing is carrying some of the weight, but the

engine still must be lifted.



I have a structural engineering type friend whom I will ask to do some

calculations. I'd like some calculations to show how much apparent weight

is on the elevator at takeoff and in a 2G turn. He has examined the wings

and has found that the 6G loading design is accurate.



Joe E

N633Z (at) BFI

CH601XL 400 hours (and hoping for more)

do not archive



P.S. I will use O2 above 12,500 feet, I've been to 17,400.

On Mon, 9 Oct 2006, Klaus Truemper wrote:

 	  Quote: 	
		   

 ......snip

 The use of sandbags on the horizontal stabilizer to lift the nose gear

 is not such a good idea. One might argue that this okay since the

 horizontal stabilizer/elevator must lift the nose gear on takeoff. But

 when the plane rotates on takeoff, the wings already  carry almost all

 of the weight of the airplane. Thus, the horizontal stabilizer/elevator

 force needed for rotation on takeoff is much, much  smaller than the

 force needed to lift the nose gear while parked.  Cessna some years ago

 had failures of the horizontal stabilizer spar of the 152 because

 people would push down on the elevevator to lift the nose gear when

 parking the plane in a tight spot.

 Best wishes, Klaus Truemper

p.mulwitz(at)worldnet.att
Guest

Posted: Tue Oct 10, 2006 2:36 am Post subject: Nose gear bungees

It seems to me that holding the tail down with the tie down ring 

would be certain to be safe.

Paul

XL fuselage

do not archive

 	  Quote: 	
		  I don't want to win a Darwin award - save me from that.

I place the sandbags at the root of the elevator, not at the outboard

ends. I will not use the sandbags if it will cause damage. I obviously,

don't think that placing 120 pounds of sand on the root of the elevator

will damage the elevator. I want to know if I'm wrong. Two G steep turns

must place more than 120 pounds of apparent weight on the elevator. I

agree that in flight the CG is forward of the landing gear and less force

is needed to lift the nose. But, on takeoff I tend to pull to lift the nose,

the 601XL is nose heavy, and that must take about the same force as

lifting the nose at rest - the wheels are still on the ground. The

'weight' on the elevator needed to rotate the nose during takeoff must be

close to 120 pounds. The wing is carrying some of the weight, but the

engine still must be lifted.

I have a structural engineering type friend whom I will ask to do some

calculations. I'd like some calculations to show how much apparent weight

is on the elevator at takeoff and in a 2G turn. He has examined the wings

and has found that the 6G loading design is accurate.

Joe E

N633Z (at) BFI

CH601XL 400 hours (and hoping for more)

do not archive

P.S. I will use O2 above 12,500 feet, I've been to 17,400.

On Mon, 9 Oct 2006, Klaus Truemper wrote:

 > 

 > ......snip

 > The use of sandbags on the horizontal stabilizer to lift the nose gear

 > is not such a good idea. One might argue that this okay since the

 > horizontal stabilizer/elevator must lift the nose gear on takeoff. But

 > when the plane rotates on takeoff, the wings already  carry almost all

 > of the weight of the airplane. Thus, the horizontal stabilizer/elevator

 > force needed for rotation on takeoff is much, much  smaller than the

 > force needed to lift the nose gear while parked.  Cessna some years ago

 > had failures of the horizontal stabilizer spar of the 152 because

 > people would push down on the elevevator to lift the nose gear when

 > parking the plane in a tight spot.

 > Best wishes, Klaus Truemper

JERICKSON03E(at)aol.com
Guest

Posted: Tue Oct 10, 2006 10:12 am Post subject: Nose gear bungees

In a message dated 10/10/2006 1:56:25 AM Central Daylight Time, xl(at)prosody.org writes:

  	  Quote: 	
		  I place the sandbags at the root of the elevator, 	


  

 Joe, Are you sure that you meant the elevator?  Or was it the horizontal stabilizer? 

  

 I would avoid placing any weight on the elevator, or any of the movable control surfaces.

  

 Jerry

  [quote][b]

xl(at)prosody.org
Guest

Posted: Tue Oct 10, 2006 10:12 pm Post subject: Nose gear bungees

Yes, I meant the stabilizer. I'm told it takes 2 - 60 pound

concrete blocks for a Piper TriPacer.



Joe E

N633Z (at) BFI

CH601XL 400 hours

do not archive

On Tue, 10 Oct 2006 JERICKSON03E(at)aol.com wrote:

 	  Quote: 	
		   In a message dated 10/10/2006 1:56:25 AM Central Daylight Time,

 xl(at)prosody.org writes:

 'I place the sandbags at the root of the elevator,'

 Joe, Are you sure that you meant the elevator?  Or was it the horizontal

 stabilizer?

 I would avoid placing any weight on the elevator, or any of the movable

 control surfaces.

 Jerry

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Oct 11, 2006 8:41 am Post subject: Nose gear bungees

You could also make a rope saddle to fit over the fuselage in front of the

vertical stab.  Put your weight on both sides.  Use plenty of weight, no

sense in having it flop forward because some one dropped a feather on the

nose.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

planejim(at)bellsouth.net
Guest

Posted: Thu Oct 12, 2006 3:20 pm Post subject: Nose gear bungees

Mike,



I agree that tne nose gear bungee wears because of steering and the small 

diameter of the tubes over which the bungee is stretched. I don't believe 

the heat of the engine is the problem.



Jim Hoak



---

planejim(at)bellsouth.net
Guest

Posted: Tue Oct 17, 2006 5:13 am Post subject: Nose gear bungees

George and Listers,

  

 My experience is that heat is not the reason for  the nose gear bungee deterioration. In my opinion, FWIW, is that the wearing and  fraying is due to bending the bungee over a small diameter tube along with a  twisting motion during taxiing when the nose gear is moving up and down.  Remember, the twisting motion, small as it is, goes on in flight too when you  move the rudder pedals. I suggest that people don't get too concerned with some  fraying of the outer threads of the bungee. The real problem arises when the  rubber bands become exposed. Just my thoughs on this from my  experiences.

  

 Jim Hoak 601HD - 912UL - 532 hours.

 [quote]   ---

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