I'm looking for information to help get to the bottom of a potential problem.
At LDRS, one customer let me know that he had had a deployment charge fire on the pad when he armed his 38mm av-bay, and that he had heard of 2 other similar situations. He found that overtightening the threaded rods was a contributing factor. I have not yet been able to reproduce this behavior, and it did not occur during product testing or during my own use of this product.
The Featherweight av-bays are designed specifically so that there are no traces to ground that could complete a deployment charge circuit on the outside surfaces of the bulkhead. That leaves a short somewhere inside the av-bay. The Raven altimeter remained in prelaunch mode and did not detect any launch. The Raven has design safeguards to prevent an inadvertent firing during power-up, and those are effective, based on results from over 1000 units in the field. So that leaves a short somewhere on the 38mm av-bay bulkhead or between the Raven altimeter and the 38mm av-bay.
I have a theory that in an overtightening situation, the active bulkhead could flex enough to bring the altimeter into contact with the threaded rod that has the main deployment charge. If that threaded rod is in contact with a ground signal on the altimeter, that would bypass the Raven's deployment switch and cause the premature firing. I'd like to collect some more information from people that this has happened to, to nail down the root cause.
In particular:
Which deployment charge went off?
Were you using the battery restraint?
Was the av-bay set up inside a 38mm coupler? What was its diameter?
In the meantime, if you're using a 38mm av-bay (and it wouldn't hurt for the other sizes either) I recommend insulating the threaded rods adjacent to the altimeter, using electrical tape or a plastic straw such as a coffee stirrer. I'll add this as an update to the manual soon, just because it's a safety improvement anyway, but I want to make sure I'm not missing something else.
Thanks for your help.
At LDRS, one customer let me know that he had had a deployment charge fire on the pad when he armed his 38mm av-bay, and that he had heard of 2 other similar situations. He found that overtightening the threaded rods was a contributing factor. I have not yet been able to reproduce this behavior, and it did not occur during product testing or during my own use of this product.
The Featherweight av-bays are designed specifically so that there are no traces to ground that could complete a deployment charge circuit on the outside surfaces of the bulkhead. That leaves a short somewhere inside the av-bay. The Raven altimeter remained in prelaunch mode and did not detect any launch. The Raven has design safeguards to prevent an inadvertent firing during power-up, and those are effective, based on results from over 1000 units in the field. So that leaves a short somewhere on the 38mm av-bay bulkhead or between the Raven altimeter and the 38mm av-bay.
I have a theory that in an overtightening situation, the active bulkhead could flex enough to bring the altimeter into contact with the threaded rod that has the main deployment charge. If that threaded rod is in contact with a ground signal on the altimeter, that would bypass the Raven's deployment switch and cause the premature firing. I'd like to collect some more information from people that this has happened to, to nail down the root cause.
In particular:
Which deployment charge went off?
Were you using the battery restraint?
Was the av-bay set up inside a 38mm coupler? What was its diameter?
In the meantime, if you're using a 38mm av-bay (and it wouldn't hurt for the other sizes either) I recommend insulating the threaded rods adjacent to the altimeter, using electrical tape or a plastic straw such as a coffee stirrer. I'll add this as an update to the manual soon, just because it's a safety improvement anyway, but I want to make sure I'm not missing something else.
Thanks for your help.
