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Re: 4P Door seal pump operation at
altitude
I've had this same problem for the last year. Problems with
maintaining cabin pressurization.
http://lancaironline.net:81/Lists/lml/Message/46348.html
http://lancaironline.net:81/Lists/lml/Message/43714.html
My serial number is 464 (c2000), so the pump from a batch is 8
years old. My problem has been them same, up to altitude
>20K, great PSI differential (5psi), but after two hours-plus, the
door cabin pressure starts leaking out slowly, PSI differential
decreases, cabin climbs above 10K and higher. If I wait, I can
see a sliver daylight between seal and frame. I might even hear
a slight wistle of leaking air (in flight, hard to tell). I'd
stuff cellophane into the gap during flight...carried a role of
kitchen plastic...to buy me more altitude flight time.
The door seal works well (5psi held for >1hr) on the ground,
holds its inflation without leak for an hour or two, the pump works on
the ground, the light comes on the panel showing power delivered to
the pump (but with engine on, who can tell if pump is running), the
valve works. I was baffled why this was happening.
I checked and serviced my Duke's valve...twice...no luck.
I beefed up the door perimeter, bringing it closer to the
seal....no help.
I occluded the pneumatic door valve/switch outflow to block
leakage. I then replaced the switch....no help.
I checked volts across the pressure sensor/switch, and found my
panel LED would come on at 9V (as the seal pressure came down and the
sensor started to activate), but my pump would not come on until
~12V...maybe...nope, not the issue.
I finally concluded with some inflight in line LEDs after the
pump that the pump was not coming on in the air despite >12V from
the sensor/switch delivered properly (and the panel light ON). I
then checked the pump with a 12V battery, and found that it gets stuck
sometimes, not running despite having power applied.
I recently ordered a new pump and placed it in parallel with the
old pump during some ground tests. Sure enough, the new one came
on and stayed on at 9V when the old one did not, when the
sensor/switch was calling for pump, even up into the 12V range.
Today I replace the door pump on the mount. Purchased from
Lancair Parts. I hope this finally solves my problem. I'm
confident it will.
Jeff L
LIVP
the
replacement pumps are 265.00.
Thank You
Michelle Gagermeier
Parts sales
Kit Components INC.
phone 541-923-2244
fax 541-548-7332
www.aerocraftparts.com
www.lancair.com
michelleg@lancair.com
My door seal
pump works fine on the ground i.e. it turns on and shuts off at the
proper pressure settings. At altitude on a long trip over 3 or 4
hours the door seal light comes on but the pump doesnıt run. I
thought I fixed the problem as I found the connectors in the overhead
somewhat loose so I secured them but now Iım finding some arcing on
the center (assuming power) post and if I use a small screw driver and
try to complete the connection the pump barely wants to start (hard to
complete circuit) it just arcs. Iım getting good alignment
between the door and airframe posts and what I assume to be good
spring pressure so Iım speculating the temperature of the
wires/posts (at altitude is very cold) isnıt providing good
conductivity to complete the circuit. Has anyone else seen this
or can assist in troubleshooting?
John
C. Bohn
Lancair 4P
N28487
Direct (Cell)-
503-887-2933
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