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Hi Georges,

I am waiting on two brand new 9.7:1 rotors to appear on my door step this week. I will measure the slots at top and bottom and expect them to be the same. Will report the results. I measured 1.98 mm at the bottom of the slot on the old rotors - where I suspect there would be less wear. But your slots appear to have more wear than mine at the top. Myreadings ranged from 2.16 to 2.26 mm at the top of the slot.

Somewhere ( far away and along time ago), I recall reading that if the slots get too worn the smooth top of the apex seal that should rub against the housing gets cocked over too far and a rather sharper edge start to rub. This and the angle increases drag forces on the seal - particularly in the center region - also the seal may start to chatter and you can see marks on the housing as periodically spaced burnish marks across the rotor housing chrome face (my rotor housings have those marks - can actually feel a faint wave pattern (valley and peaks in the housing surface). When the drag forces reach some point the apex seal breaks - once it breaks its only a matter of time before the pieces leave the slot.

Ed A

----- Original Message -----

From: Echo Lake Fishing Resort (Georges Boucher)

To: Rotary motors in aircraft

Sent: Sunday, April 17, 2005 10:57 PM

Subject: [FlyRotary] Re: Apex Seal Groove Wear

Hi! Kelly

I must of mist Lynn's VST system, I don't understand what those measurements are. I opened another 91 13b NA today & to my dismay it was toast (supposably a Mazda rebuilt in '99)

I measured at 90deg. to the apex slots with a digital vernier caliper the reading I got on this one were from 2.26 to 2.43 mm the new 2mm seal is 1.91 to 1.94 wide, the max allowable clearance is 0.1mm therefore in this case the widest width should be 1.04mm so this slot has 0.39 mm excess wear at the slot opening. Has anyone actually measured a new rotor? I guess I will buy 2 new rotors now

Georges

-------Original Message-------

From: Rotary motors in aircraft

Date: 04/17/05 15:33:47

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: Apex Seal Groove Wear

Georges,

Have you tried Lynn's VST (Vertical Seal Test) for apex slot wear and if so

what measurement did you get ? Lynn suggests that 3/16 inch (.1875 inch)

or 4.7625 mm as the outer limit........Of course after all the posts on this subject

everyone may have their own personal limit !!

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Echo Lake Fishing Resort (Georges Boucher)" <echolakeresort@telus.net>: --------------

Hi! Leon

You have a point regarding air filter use on water, when Mt St Helen (Washington state) erupted the first time I had a shop in Vancouver BC Canada (about 300miles away) even at that distance, one of the fleets of vehicle that we serviced had to have the air filters replaced every second day( even a week the eruption).

I made the crack about no need for an air filter for a float plane in Canada, but actually much of the time float planes are started on the lake shores with the engine above the ground instead of the water. The other thing about air filters on an airplane, an alternate air source (like a slightly spring loaded flat) should be supplied ( in a float plane case , water could splash onto the element & freeze solid at altitude, blocking air to the intake). On the rotor apex seal subject, I agree with you regarding the amount of wear on the rotor seal slot & seal has to be a lot more than Ed's to spit out the seals. I drove my used engine supplier nuts yesterday, measured 6 different rotors & all were from 2.13 to 2.28 mm, he old me they use these rotors regularly for a long time & never had a problem. Mine are 2.17 to 2.26mm, So I guess I'l have to buy new rotors.

Georges Boucher

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