In a message dated 9/25/2010 11:15:26 P.M. Eastern Standard Time,=20 david.staten@gmail.com writes:

Attached=20 are links to video, stills and pilot testimonial to a piston racing engi= ne=20 installed in Relentless NXT hand grenading from loss of engine oil press= ure.=20 Prop to flat pitch, engine seized due to oil loss, prop hub and blades= snapped=20 off and the sound was impressive. Pilot then made a deadstick safely, an= d CFR=20 hosed down the engine cavity.

Let me speculate further.

The oil line/fitting to the prop governor fails. The prop goes to fin= e=20 pitch. The engine fails from mechanical

over-speed, not loss of oil pressure. Looks like it pulled a rod into= two=20 pieces and beat itself to death.

Although the pilot chose not to trade excess speed for altitude in th= is=20 case, and did a fine job of recovering the aircraft, it may be a better ch= oice=20 if you are not in the center of a big airport to capture that energy while= it is=20 available. For us slow thinkers, lots of altitude means more range and mor= e time=20 to think.

Not pointed out was the aluminum fitting failing through the threads.= In=20 almost all cases a "Bending" failure will be "Through the threads" That is= where=20 the smallest cross section is and the greatest concentration of stress ris= ers.=20 The question should be: How did this fitting get itself into a bending loa= d?=20

Was that "B" nut tightened without backing the fitting up= with=20 the correct aluminum wrench or was it a Chinese fake Crescent wrench? Was= there=20 an Adel clamp close by to take up the weight of the hose in those high G= =20 turns?

The other favorite activity among the unwashed is to turn the fitting= with=20 the pipe threads just another 1/4 turn to get the other end to point in th= e=20 right direction. Keep a selection of such fittings and from different=20 manufacturers, and hand select the one that goes in with the correct torqu= e and=20 ends up where the free end needs to be. Over torque the fitting to get the= =20 direction right is a bad idea. A damaged 90 and an undamaged 90 look the= same=20 and go back into the fittings drawer to be used years later on your friend= s=20 airplane.

Or use a straight fitting with a 90 degree hose end or better, a swee= p 90.=20 And support the hose per the catalogue.

There are rules for installing hose and fittings. Found in every hose= =20 catalogue.

And yes, I have pulled a few rods apart on the dyno.

Lynn E. Hanover

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