ggower_99(at)yahoo.com
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 Posted: Tue Mar 07, 2006 10:06 pm Post subject: Grades of Nuts & Bolts (long) |
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Got it, sorry Jerry... Just got a little lost 
My personal experience of almost 15 years flying 80% of the weekends here using almost all the Rotax engines (447, 503, 618, 532, 582 and now 912S) also with the experience of all the ultralight pilots in our Club, and half of the country (as a Builder Adviser), never had or got refered a problem with the metric bolts that come with the engine or their replacements (Grade 8 or a AN European equivalent?) when used as propellers attachment.
We also used almost all type and brand of propellers known, USA and Europe, Composite (adjustable) with alum center part, all wood, wood blades (adjustable) with alum center part., etc...
We always torque and retorque as specified (Factory and Mantainance manuals).
As I told early, torque is 99.99999 % of good service, all adjustables every 25 or 50 hours (at least once a year). Wooden every change of season (at last at the beguining of dry and also rain season).
Normally Rotax bolts are installed in treaded hubs (tight and torqued) and they also use an extra nylon safety nut as "double tight" (sp?), instead of the safety wire.
To retorque, we remove first the safety nylon nut, then retorque and reinstall a NEW safety nut. Safety wire ones, as normal procedure...
I remember... Once did happened here a lost prop in flight, not because of the bolts, but was a funny (and safe) event:
This pilot was the first and only Trike (weight shift) Pioneer and Instructor here at that time. We all (trike flyers) learned to fly with him...
His old trike, well mantained, with already several new wings, but the same old Robin engine with a cog belt reduction, they had all the hours in the world (no hourmeter, no logs, good old times), that engine never missed a beat, always started at the 3rd hand pull (no starter or cord pull), primed in cold or with engine hot, always just 3 pulls and started... was amasing.
One Saturday, we were all in the Clubs terrace, he landed with the engine stoped (he used to do it normally to practice engine out landings with his students). He walked to the group and with his characteristic calm voice asked: "Have you seen a propeller?" " I just lost it in flight".
Imagine the face of all of us!!! "WHAT?" We all looked around and found it half our later...
What happened was that the reduction and the hub were a single machined piece, fortunally had a safety shaft inside the reduction. The red/hub failed exactly in the middle and the prop just flew away backwards, when lost speed (and pressure to the engine over the shaft) he was flying over the club when happened so while gliding he had the chance to see the prop for several minutes until lost its sight...
The reduction was rebuilt in my factory's lathe and two years later was "forced donated" to our Clubs Museum, where is waiting "restoration"
Saludos
Gary Gower.
JERICKSON03E(at)aol.com wrote:
In a message dated 3/6/2006 9:37:44 PM Central Standard Time,
ggower_99(at)yahoo.com writes:
No, not at all. What problem do you had?
Saludos
Gary Gower
Gary, No problem as they are not yet installed.
My question was sent to add the metric bolts to the subject, rather than to
ignore them.
Prop bolts are the ones we need to know about, and maintain often.
Do you happen to know how the metric bolts fit into the grade 8/ AN/MS
strength question?
Regards, Jerry
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