REFLECTOR: Nose gear didn't lock

[Scott Derrick]

I checked today and it was the micro switch lever arm.  It needed to be
bent just a tad more to cause the switch to indicate a down and locked
position. 

Scott

Glenn Babcock wrote:
> Scott,
>
> The purpose of the gas spring is to help push the gear over center
> when using the dump valve.  Opening the dump valve releases the
> pressure on the hydraulic cylinder and the gas spring will then be
> able to push the overcenter linkage to the limit.
>
> But when the gear is operated by the pump the hydraulic cylinder is
> pushing the overcenter linkage and overpowers the gas spring easily. 
> So what you need to look at is the hydraulic system.  Perform a
> retract test and using the gear pump as usual lower the gear.  Try to
> reproduce the scenario where the gear switch is down, the pump has
> stopped but the nose gear light is not on.  Then check the position of
> the overcenter linkage and see if it is touching the stop inside the
> keel.
>
> If not, you may have a bad pressure switch, a bad hydraulic cylinder,
> a blocked line, or some other issue causing the gear pump to stop
> before the cylinder reaches the end of its travel.  Try opening the
> dump valve and see if the linkage moves any further.
>
> It's also possible it's just out of rig.  If so, you need to find out
> why. For instance, did the rod end jam nut come loose?
>
> When the system works correctly the cylinder should extend to its
> limit with the overcenter linkage just touching the stop.  It should
> NOT press against the stop, the pressure must be carried by the
> cylinder.  The linkage should be ~1/4" past center.  The gear pump
> stops when the cylinder reaches it's limit and the pressure increases
> in the system, causing the pressure switch to open.
>
> I had a similar issue and it was a bad pressure switch.  Once I
> replaced it the system was back to normal.
>
> Regards,
> Glenn
> N697RG SERG (flying)
> http://lakenormanairpark.org/
>
> --------------------------------------------------
> From: "Chuck Jensen" <cjensen at dts9000.com>
> Sent: Thursday, October 08, 2009 8:17 AM
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Nose gear didn't lock
>
>> Scott,
>>
>> During the ground retract test, when you didn't get the green light,
>> did you check to see if the assembly was over-center?  If it was,
>> then as Terry suggests, your proximity switch may need to be
>> adjusted.  But if you use your stick and find that you have to nudge
>> it a little to finally go over center, then your light is good but
>> you have a mechanical issue, be it spring or whatever....that's
>> waaaaaay above my pay grade.
>>
>> Chuck
>>
>>
>>
>> -----Original Message-----
>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
>> Behalf Of Scott Derrick
>> Sent: Wednesday, October 07, 2009 9:42 PM
>> To: Velocity Aircraft Owners and Builders list
>> Subject: REFLECTOR: Nose gear didn't lock
>>
>>
>> On my last flight when I let the gear down I had a unsafe light and the
>> nose gear light was not lit, the pump light indicated it had shut off, I
>> gave a little jerk on the stick to increase the G force momentarily and
>> the green light came on.
>>
>> later I was performing a gear retraction to test, when I let the gear
>> down I got the same indication. I kicked the nose gear tire and the
>> light came on.
>>
>> Is this a symptom of the nose gas strut going soft?
>>
>> I have previously in the last couple months made 20+ retraction tests
>> with all OK.
>>
>> Scott
>>
>>
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