REFLECTOR: N21HV Engine starts (or "No Shoddy Work Goes Unpunished")

[Hiroo Umeno]

Short Summary:

At 12:30pm on August 1st, my plane "N21HV" made its first "airplane noise" without my vocal assistance.

 

Details:

8/1 was to be "the big day" as the DAR was scheduled to pay a visit at 1 for final inspection and issuance of the provisional airworthiness certificate.  Steve Murphree flew in (commercially) from Reno for final factory approved inspection and flight testing.  We spent all morning going over the plane in minute details and he was satisfied with the workmanship and the general condition of the plane.  Steve had a few improvements suggestions but nothing that precluded us from flying the aircraft safely.  I was quite satisfied to know that all the critical measurements were well within the factory specified spec.

 

We broke for lunch and gathered around the plane around 12:30.  At this point, one thing we have not done was to actually "light the fire".  We had 30 minutes or so before the DAR showed up so we looked at each other and said "Let's fire it up!".

 

With Steve, the test pilot, at the controls and two mechanics kneeling about 20 feet away on both side abeam the engine with fire extinguishers, and me behind the camera, the electrical fuel pump was turned on for a few seconds, followed by the starter.  Steve had to pump the throttle a couple times but then, just like magic, the plane started making "airplane noises" on its own.  About 1 minute into the engine run, the two mechanics spotted dripping below the speed brake and waved off.  As Steve secured the plane, we saw that what started out as drip-drop, quickly developed into a waterfall of fuel gushing from the cabin floor.  After making sure there was no ignition source, I ran to the airplane and pulled on the fuel-cutoff which did not have any effect.  We climbed in and manually clamped off fuel lines from both strake tanks as we were certain the problem was after the tanks.  By this time, the cockpit floor on the pilot side had about ½" of 100LL.  We placed a bucket below the plane to capture the fuel, which was about 1 gallon in it by now.

 

In the middle of all the excitement, the DAR showed up.  Not the best time to "inspect" the plane...  He was really good natured about it, though.  Something about "we call these things 'experimental', right?"

 

We had to drill a small hole on the floor above the speed brake (air drill of course) to drain the puddle on the floor, and then evaporated much of the remaining fuel using the compressed air blower.  It's amazing how fast fuel evaporates.

 

We pulled the header tank and discovered the source of the problem.  The header tank is constructed from two pieces of pre-molded fiberglass parts.  It was one of the earliest fiberglass layup I had done (before I had consistent working procedures).  There were areas where the glass did not cover the joint and was held by resin alone.  Amazingly, this has held all this time through multiple fill - drain cycles, pressure testing, leak testing, etc.  However, running the engine has introduced another element into the equation in the form of vibration.  This cracked the weak joint in a matter of 50 seconds or so resulting in fuel being dumped into the cockpit.  Since the fuel shutoff comes after the header tank, it had no effect.

 

The good news here is that we found the problem on the ground very quickly, root caused and remedy being applied.  The engine ran a bit rough but I am guessing that it will smooth out as it breaks in (it is a fresh 0 timed engine).

 

A day and a half later, the sump is now repaired and I am planning on doing another starts Friday morning.

 

Hiroo

 

 

 

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