Had a GPS antenna fail mid-flight over Phoenix last month

I was on a King Air 350 coming back from a maintenance test flight near Phoenix when the copilot's GPS unit went completely dark. No warning flags, no error codes on the MFD, just a blank screen where the position data should be. We landed fine using the other unit, but after I pulled the antenna off the roof I found water had gotten into the coax connector and corroded the center pin. The sealant around the base looked fine from the outside, but a tiny crack let moisture in after a heavy rain the day before. I ended up replacing the antenna and repotting the connection with new sealant, then ran a full GPS ground check for 30 minutes. Has anyone else seen water sneak past a good looking seal on these older King Air antennas?

2 comments

2 Comments

valsullivan14d ago

Yeah, had the same thing happen on a Cessna 340.

-1

emma76814d ago

Did you ever figure out what caused it on your end? I had a similar thing in a Seneca once and it turned out to be a bad ground strap on the alternator. Took me three trips to the mechanic before they caught it.