T

terry.mortimore

Well Known Member
Hi Gang:

I'm currently shopping for a crankshaft for my IO-320 150 hp engine. I will be running a 4" extension to go along with my Sam James cowl.

Some of the crankshafts I've seen have lightening holes in the propeller flange area.

Would it be wise to use this type of crankshaft with a prop extension?

Any body out there using this combination?


Thanks, Terry.
 
CRANKSHAFT

What kind of prop?? This is the main issue. I personally would be ok with lightening hole crank with wood prop or maybe even MT, but not with a metal fixed pitch or constant speed. Having said that I have a non lightening hole crank for the 0 320 I am building. Watch out for corrosion in the front main bearing bore. (505)
 
Hi there, I should have included the prop information.

I'm trying to hold out until the sensenich ground adjustable propeller is released for the 320 lycoming. They are projected to be pretty light, but it's been a while since I looked at the spec's.

If they don't come through, I will be using their metal fixed pitch prop.



cheers, terry
 
not a problam

I have the old crank in my 200hp IO 360 with an MT prop, My friend from Lycoming who helped us with the engine said they only changed the crank flange because people like Shawn Tucker where breaking the old ones with the holes in the flange and that this crank would not be any problem with whatever prop for normal flight and gentleman aerobatics.
 
I will be running my O-360 with a metal FP and a 2-1/4" spacer and a crank with holes. Never heard of someone losing a prop with this combo. At least a normal sane person that cannot tolerate 12G's!

Tons of these cranks out there....
 
LIGHTENING HOLES

Twin Commanches which date back to 1963 allegedly had some problems with cracks between the lightening holes. Hartzell lightweight constant speed with long integral extension. I don't know any specifics on the Twin Commanche problems except there was a handbook change that prohibited operation at certain power settings.
 
Dynafocal 2 mount.

My -4 originally had one of these engines on it and we still build these engine mounts for the RV-4, one every couple of years.
 
The original factory demo Lancair 320 had the older flange with lightening holes. The crank had an AD against it prohibiting aerobatic maneuvers. Well, they did aerobatic maneuvers (loops and rolls), in their promo video. A few years later the prop and flywheel departed the aircraft and killed the factory pilot.

<<(AD) 65-03-03 (referencing Lycoming Service Bulletin 300B). This AD requires visual or magnetic particle inspection of the propeller mounting flange before the next flight following certain aerobatic type maneuvers not approved for normal category aircraft. >>

<<The crankshaft flange was examined by the NTSB's Metallurgical Laboratory in Washington, D.C.. The NTSB metallurgist's factual report on the crankshaft flange stated "...examination of the propeller mounting flange showed that five of the six fracture areas between lightening holes contained evidence of fatigue cracking.">>

full report is here:
http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20001208X06424&ntsbno=CHI96FA278&akey=1

Personally, I would stick with the newer models, if for no other reason than added safety margin.
 
Accedent report!

I read the report and it states the flange is or was .255? the flange on my IO 360 A1A is at least in the neighborhood of .500? therefore this is not the crank flange my Lycoming buddy said to use with no worries. I retract my statement, I have no idea about this crank and I would read the AD and decide for yourself if it is suitable for your use.
 
Yep my comments are for the thick flanged model not the thin flanged one mentioned above...
 
You must log in or register to reply here.