Wednesday, March 26, 2014

Vacuum Failure IMC

08Romeo, IMC with rain
I was reading a post on the AOPA forum about Vacuum Failure in IMC. The pilot posting provided a good account of the events which resulted in a positive outcome. As an instrument rated pilot I would expect nothing less, that's what we train for. I guess that comes off as a bold statement having never had to deal with this issue. Looking back at my training and all that partial panel time I would hope I handle things as well as this pilot did. Sure, we all practice partial panel but the pucker factor isn't there like it is in the real world situation. Put yourself in this pilots place, family on board and thankfully this time only a layer to descend through.

Here is the pilots account of his vacuum failure in IMC.

"We were returning from Summersville, West Virginia this morning with two dogs for a Pilots N Paws rescue flight. We were IFR at 8,000 feet, in the clear 4,000 feet above a solid undercast. The flight down and back had been uneventful until we were just northeast of Columbus, about 40 miles from home. As I was scanning the panel, I noticed the VAC light was illuminated. I pressed the test button to make sure it was in fact lit, then looked at the vacuum gauge, which was resting all the way to the left on the zero. The AI and the DG had not started to tumble yet. I told my wife we lost our vacuum and that those two gauges were no longer reliable. She didn’t seem too concerned. I knew the weather at home was 22SCT 33OVC, so I was pretty sure we would not need to shoot an instrument approach partial panel. I would, however, need to descend through the clouds to reach VFR conditions. I was just about to tell Columbus Approach of my situation when they handed me off to Mansfield Approach. I called Mansfield and advised the controller of the situation. He acknowledged and asked what I wanted to do. I told him I would descend and hoped for a visual approach. He didn’t seem too concerned, as I was not, either, and cleared me to descend to 3,000. By this time the AI and DG were obviously not working, so I covered them. As we entered the clouds, keeping the wings level with the turn coordinator was easy, although we got off our direct course a bit. I wasn’t too worried about that, as the G430 made that part easy to correct once we broke out of the overcast. The bases were right at 3,000, and I really wanted to proceed VFR home, so I quickly advised ATC that we were in VFR conditions and would cancel IFR. They acknowledged and said good bye. We were still about 22 miles from home and just flew low the rest of the way and landed without incident.

It was a situation I, and all other instrument rated pilots have trained for, and it really was just like training. No big deal, not an emergency, although if the weather had been any lower, we would have needed to do an approach partial panel, but, again, that would have been okay, too. Glad it happened on the way home, though."

I read through this post and asked myself if I practice enough partial panel and my answer is no.  How often do you practice partial panel? What systems do you have in your aircraft to provide redundancy?
Precise Flight Standby Vacuum System
Our Sundowner has the Precise Flight standby vacuum system with the low vacuum warning light. The sooner you are made aware, the quicker you can deal with the issue. I have been researching and giving some serious thought to purchasing the Sigma-Tec electric attitude gyro. Here is a very good article on vacuum pumps that I stumbled across, it's worth the read. Dry Vacuum Pumps


ザイツェヴ said...

Sigma-Tec unit is hardcore. There's also a bunch of cheaper electrical gyros for backup, some claim to conform to TSOs (such as RCA). Personally, I would rather add a 3" EFIS such as MGL or AvMap. They are uncertified, but they are good for backup and have batteries, which Sigma-Tac lacks.

Gary said...

ザイツェヴ , Adding the EFIS MGL or AvMAp would be an efficient and welcome savings. However, they can not be a permanent addition to a certified aircraft. I can't even make the Garmin 496 a panel mount with ships power connection.

Craig Gomulka said...

great post, thought provoking and a good reminder. Thanks Gary!

Gary said...

Craig, One just has to love the cloud busters forum on AOPA and cleared for the approach on POA. Always good posts to make you think about those what if situations.