ARINC 429 bus went silent mid flight last Tuesday

I was troubleshooting a comm fault on a CRJ200 and the number 2 MMR just quit talking on the bus. Turned out the connector backshell had backed off about a quarter inch and pulled the pins loose. Anyone else run into this on the Collins units?

2 comments

2 Comments

verap527h ago

Pretty sure @leow90, that zip tie fix is gonna bite you later when it traps moisture and starts corrosion... Seen that happen on a few MMRs that came through my shop. The real fix is just torquing the backshell to spec instead of leaving it hand tight.

leow908h ago

Yeah the Collins MMRs have that issue where the backshells don't lock tight enough. I've seen it happen three times now on different jets. The vibration over time just works the connector loose. We started putting a small zip tie around the backshell and the base of the connector as a cheap fix. Also if you pull the backshell off and check the contacts you'll sometimes see bent pins from partial engagement. That's the real headache because you gotta repin the whole thing.