lml@lancaironline.net Mailing List Archive

Angier,

Solenoids that open and close while carrying large currents need to open and/or close with more force and speed so they do not weld themselves shut. Sometimes you will see different ratings for 'make' and 'break' (close and open). The springs in these relays are quite a bit heavier and so is the coil. You will note a much higher current draw on a starter vs. master solenoid coil.

When dropping the gear during an actual emergency extension, I would suggest slowing to 80 KIAS before opening the dump valve. This will allow momentum from the free-fall aid in the extension. If dropped at a higher speed the gear essentially comes to a stop and it is then gas strut vs. air load.

During in-flight checks it is useful to drop the gear at a higher speed to check the health of the gas strut. A healthy strut should get the gear down at 100+ KIAS. During a real free-fall you want to stack the odds in your favor and slow down first.

Chris

Chris Zavatson

N91CZ

360std

http://www.n91cz.net/

From: "Greenbacks, UnLtd." <N4ZQ@VERIZON.NET>
To: Lancair Mailing List <lml@lancaironline.net>
Sent: Monday, March 25, 2013 4:43 PM
Subject: [LML] Re: Hydraulic gear pump failure

About 3 mos ago, the high side relay failed while 4ZQ was up on jacks. I figured that old age (original kit) plus X number of cycles during construction took that relay to the end of its useful life. So trying to kill two birds with one stone, I replaced both hi/lo relays with new (chinese) from the local auto parts store.

The cause of yesterday's gear failure turned out to be the NEW low side relay, and it had just 14 cycles....

So, on the assumption that relay quality differs, who makes a HIGH quality relay with the same footprint as those that
came with the kit? Any reason why they should not be continuous duty type?

Angier Ames
N4ZQ
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