Richard,

Well, this doesn't help improve the insurance company's Lancair risk calculations.  You wrote:

 "... did GUMPs last time on short final.  This time, looked at lights, all OUT, gear switch down, no yellow.  Hmmm something’s amiss here…!?  Gear lever is down, why are lights out?! Circuit breaker is in, not popped.  Concentrate on landing......" 

Did "Go around" ever enter the list of possible actions?  How about the instructor's thoughts?  You had the opportunity to practice a non-emergency power up and then to fly away from the pattern to resolve an issue clearly indicated by the missing gear lights.  Landing with an unknown status of the gear could have been fatal since the lack of green only means they are not locked down - there is no other information about each wheel position.  This was a perfect situation to initiate the emergency gear extension checklist at a safe altitude and speed.  Oh well.....

I am pregnant with expectation of your A&P's further analysis about the failure.  It could be costly in time since it appears he is not familiar with Lancairs.  If the system was wired per Lancair instructions:

Down ops:  lo amperage power from the "relay breaker" goes thru the switch in the down position, thru the pressure switch and thence to an intermittent relay coil if the pressure is low enough.  If the relay is energized, hi amperage power from the "pump breaker" passes thru the relay contacts and on to the down side of the pump motor.  A tap off the relay contact provides power to the "transition" light (from power going to the pump).  Once the hydraulic pressure is high enough, the pressure switch opens and removes power from the relay coil - thus removing power from the motor and transition light. 

Up ops:  Change the word "down" to up" in the previous description except that there may be a "squat" switch before the pressure switch to prevent the gear from being retracted before flight.  Most commonly this is an air switch that closes above 70 KIAS (plumbed to the pitot).  Perhaps this explains the reference to a "console bypass switch" and such a switch is used to allow retraction of the gear while the plane is on jacks (or in a sling).

So, If the master switch is on, how could the gear switch be in the down position with the gear retracted and both the relay and pump breakers engaged?  Could the power be removed from the down circuit and somehow applied to the up circuit without moving the gear switch?  Could the pump power bypass the relays?  Could the down relay open on its own and the up relay close on its own?  These conditions are not likely.  Could hi pressure be present at both pressure switches, thus preventing the motor to act (as sometimes reported here) - oh, that would have meant the gear never came down (no green lights, no transition light). 

Your description is puzzling.   Remember that you said that the gear was up and tightly stowed - thus, they were held up only by hydraulic pressure.  While in the sling, if the master switch was turned on and the switch was in the down position, the gear should have powered down unless the down pressure was also high or the relay breaker (fuse) was open.  Moving the switch to the up position didn't matter because the pressure was holding the gear up or the squat switch (if present) would not allow any power to reach the up relay.  You had an opportunity to further test things if, after opening the dump valve, you would have re-engaged the pump breaker to see if the motor would start.  Oh well....

This is going to be interesting.  Keep us posted.

Scott Krueger

Here’s the email I did not want to ever write but if someone knows or has insight, I need your thoughts.  This morning with my instructor in my Lancair 290 we took off to do a trip around the pattern at our local airport.  It was clear sky, unlimited visibility.  He and I performed a normal run-up, by the book with no issues.  Radio check, no issues, took off and gear-switch up at point of no landing, no issues.

As we were going to just do a simple landing, on downwind I did my normal before landing checklist, slowed to gear down speed 120 kts and did my GUMPs.  Gas on correct side, fuel pump on, Undercarriage, gear down and three green, check.  (Instructor right seat audibly verified.  They are very bright green lights! And a bright yellow in-motion light illuminates)  Mixture full rich, Prop max RPM (MT electric prop).  Airspeed with gear down very quickly drops from 120 to 100 so twisted in 16” on throttle from 13”. 

Announced base turn, put in more flaps, did GUMPs again.  Fuel correct. Again, same verification three green! Mixture full rich, throttle twisted tight (high rpm).  Airspeed 95 kts.  Right on glideslope.  (VASI lights good). 

Announced final turn, put in all flaps, did GUMPs last time on short final.  This time, looked at lights, all OUT, gear switch down, no yellow.  Hmmm something’s amiss here…!?  Gear lever is down, why are lights out?! Circuit breaker is in, not popped.  Concentrate on landing, PING PING  PING of blades and shooosh of composite on asphalt.   Slide to a stop and look at instructor who is looking at me.  What happened???  We had THREE GREENS on downwind and base, and gear down switch is STILL DOWN!

Ok, if I was reading this I’d say sure, you imagined three greens didn’t you?  But before you say so, we climbed out of the plane, and after a crane arrived picked up the plane the gear was cleanly stowed.  Moved it off the ramp and had an A&P the first person to check it while still lifted up by the crane.  Everything turned on, electronics, radios, etc.  No circuit breakers popped.  But the Gear Down switch (which was still in the down position) did NOT move the gear down or up, nor start the hydraulic motor.  No smell of any burnt wiring, etc.  A&P moved the gear switch up and down with no effect.  Pulled and reset the dedicated hydraulic pump breaker, no effect.  Checked the locking center console bypass switch, correct position, and finally A&P asked me if there was a bypass.  I pulled the hydraulic pump breaker and flipped the hydraulic lever bypass and the gear dropped.  We pushed the nearly completely extended gears to full lock position, and got THREE GREEN. 

We were about 50 feet above the ground on very short final when on the 3^rd GUMPs I noticed the lights out, but with the gear down, and having seen three green 2x and verified by the instructor, I’m at a loss as to what happened.  All points to the gear retracting which makes me think there must be short somewhere…

So now off to meet the FAA guy, call the MT Prop guy, getting ready to call the insurance guys…

Lovely day to fly indeed!

Regards, and remember it’s not if, but when…

Richard Neal

 

 

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