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Posted: Sun Feb 14, 2010 9:42 pm
by Johan Nortje
This morning on my way to the Augrabies waterfalls my left main wheel broke off as soon as I started to taxi. As I apply brakes for a brake test the wheel just broke off. Think of what could have happend on landing or take off.
I cannot remember when or even if I ever had a hard landing with ZU-EID. The axle broke off at the point where it was welded.
All the main wheel components was bought from Aircraft Spruce. Attached photos. Russell I will sent you the broken axle for inspection. From the beginning this 16mm "pipe" has bothers me.
I do not trust them anymore, and think of replace it with a solid steel bolt. Will a 8,8 steel bolt last? The clever guys say that a "pipe" is stronger than a bolt.
Any suggestions?????????


Posted: Mon Feb 15, 2010 9:48 am
by whisper
I have no idea what axle you have used. I have never seen one like that before. The only axle we recommend is the Grove 5018 as specified in our manual, pricelist, pictures, videos, blog etc. See attached.
I would strongly recommend that other axles not be substituted in place of the 5018.

Also I see from the pics that you have used M8 bolts (?) to attach to the gear leg. This would have involved drilling out the spring steel gear from the 6.3mm (1/4") holes as supplied. Apart from the reduced edge distance resulting from the bigger holes there probably would have been heat build up etc involved with drilling hardened spring steel. This is not a good idea.

I'd strongly recommend purchasing the correct axles, brakes etc from Grove or Aircraft Spruce.


Posted: Mon Feb 15, 2010 10:43 pm
by Dave
Hello Johan

Man, I'm sorry to hear of your mishap.

I've been there, done that, & got the T-shirt
and yes, I DO know what it's like on landing - not fun !

Johan, there's 2 things I ALWAYS tell Whisper builders, because I've been there myself.

1 Fit a finger strainer in the tank - engine failure at tree top height is heart stopping, scary stuff (2 times)

2 Please, please use the Grove wheels; the axle & rims & bearings are big and solid and beautifully engineered real aircraft
quality, just like the Whisper.
The cost & weight saving on a lightweight set are just not worth it. (also 2 times) Remember, 750Kgs / 1650lbs at gross !!!

There's plenty of time to get a Grove set landed (ha-ha) and fitted before the fly-in
Looking forward to seeing you at Gariep



Posted: Sun Feb 21, 2010 9:02 pm
by Johan Nortje
Thanks Russel and Dave,

For the info and recommendations. Yes it is true ---- do not buy cheap.
There is a saying in afrikaans "goedkoop is duurkoop". Luckily there was no damage, not even to the wheel spats.
I will replace them with grove axles and wheels as soon as I saved the money.

How do you get a finger strainer in the tank. Is it possible to insert it through the outlet.
I have no idea how it looks or how it works.


Posted: Fri Mar 12, 2010 3:57 pm
by Dave
Hi Johan

Good for you on the wheels...

The finger strainer is really simple to fit.
I drained & removed the tank & then cut off the aluminium fuel pipe outlet, which
came out the really thick plate at the bottom of the tank.
I then drilled the bigger hole for the strainer, which uses a standard BSP
pipe thread. I borrowed the tap from a plumber, tapped into the thick plate & screwed in the strainer. A normal brass pipe fitting outlet screws into the bottom of the strainer, to connect to the fuel pipe. The whole process took less than an hour.
The part from Aircraft Spruce is $5.85. Placo locally will get it for you for not much more
Don't use PTFE tape to seal the thread; use the Locktite stuff for fuel seals (PTFE plumbers tape strips into thin slivers when tightened and gets into your pipes - a friend had an engine failure because of this!)
One more thing, don't ever use silicone near petrol - petrol dissolves silicone !!!
NB, NB, NB: THOROUGHLY clean the tank of filings before you put it back; it's amazing how much gunk gets in there
Here's a pic and notes from AS
Finger strainer.jpg
Finger strainer.jpg (20.56 KiB) Viewed 13809 times
Finger strainers are strainers for fuel tank outlets. Standard size features a brass fitting with 3/8" male pipe thread which fits AN867-3 welding flange, and 1/4" female pipe thread for valve or fuel line fitting. Screen is 16 mesh brass.

I hope this helps


Posted: Mon Mar 15, 2010 9:02 am
by whisper
That finger strainer is on our standard parts list that you order from Spruce. Our tanks come threaded to accept it directly with no tapping.


Posted: Fri Mar 19, 2010 2:53 pm
by Johan Nortje
Russel and Dave,
Thanks again for the info.
The firm that builded my tanks did not fit finger strainers.

I also learned my lesson with silicon, which I used to seal the electric fuel flout on top of the tank.
The petrol turn the silicon into a solt jelly that blocked the fuel filter. Luckily the whisper can fly without an engine and I managed to do a save landing. After I inspected the tank I found a few more "silicon droppings" in the tank which I removed.

A dry silicon dropping 2mm in size become more the 10mm in size when socked in petrol, and that silicon jelly is then easily sucked into the fuel line and block the filter or the water strainers inlit.

Safe flying


Posted: Sat Mar 20, 2010 9:38 am
by PeterB
when i fitted my finger strainer i did not use anything to seal it with and it leaked.

i then used some special stuff and it sealed perfectly ...... it was not silicone


Posted: Sun Mar 21, 2010 8:55 pm
by whisper
I force landed a KR2 on the kyalami main straight in the 80's because of one blob of silicon in the tank and no finger filter......that episode resulted in me taking a fond liking to finger filters and long wings :)