What does prop rpm have to do with AHRS?

[Sidebar]

^ +1

[CID]

http://static.garmincdn.com/pumac/190-01051-00_0A.pdf

The Garmin AHRS uses MEMS sensors, not gyros like rigpiggy says. I didn't mean to imply they were classic AHRS units.

[rigpiggy]

i like how the picture on 1-2 shows where not to mount on a KA200 the radio bay haw haw

[pelmet]

By the way, most AHRS actually use strap-down mechanical gyros. Laser-Ring gyros are mostly used in IRS systems but there are a couple of AHRS that use them.

A strap-down gyro is different than a typical gimballed gyro in that its movement is restricted. Instead of measuring the displacement between the gyro and gimbal a measurement of the forces of the restricted gyros are taken. This force is proportional to the angular rate of change along the gyro's access.

My understanding was that a laser gyro(non-mechanical gyro) is a strapdown gyro.

[pelmet]

I am fairly sure that the garmin uses "tuning forks" not gyros that sense acceleration by the change in frequency "doppler effect, they have 3 for the different planes run thru a mixer " computer" translating to a signal for the display. it is conceivable that the natural oscillation frequency had some resonant effects at the 1920-1960? rpm. Some light reading to the concept.

http://www.pprune.org/tech-log/print-33 ... -86-a.html
http://www.avweb.com/news/features/mems ... 787-1.html

http://evaluationengineering.com/articl ... course.php

Thanks,
That may be the answer I was looking for.

[CID]

pelmet, not really. A ring-laser gyro is sometimes referred to as a "strap down" type because it's not gimballed. But it can't really be compared as it measures the displacement of light to determine movement. A strap-down gyro technically is a rotating mechanical gyro that is not gimballed. Instead of measuring the displacement between the gyro and gimbal, a strap-down gyro is forced to move and it's opposition forces are measured to determine movement.

[pelmet]

pelmet, not really. A ring-laser gyro is sometimes referred to as a "strap down" type because it's not gimballed. But it can't really be compared as it measures the displacement of light to determine movement. A strap-down gyro technically is a rotating mechanical gyro that is not gimballed. Instead of measuring the displacement between the gyro and gimbal, a strap-down gyro is forced to move and it's opposition forces are measured to determine movement.

According to the FAA Handbook of Knowledge.....the definition of a "Strapdown System" is an INS in which the accelerometers and gyros are permanently strapped down or aligned with the axes of the airplane. I guess the laser stuff and the non-gimballed stuff you mention both fit the definition.

https://books.google.ca/books?id=1HZtBQ ... aa&f=false

[bobcaygeon]

Garmin overlooked/didn't anticipate the 3 bladed prop vibration issue with this AHRS. Just another case of an STC being certified for one configuration and blanketing the rest. The advisory is brand new (Jan/15).

Declaring an emergency is a no brainer to me, the old culture is wrong. The emerg. vehicles like the practice and I pay way too much in NavCanada fees to not use the services if I might need them.
I was lucky and learned how wrong the old mentality was when I was inexperienced. My old school captain actually said "Good pilots don't go around". He should have asked his passengers what they thought of that statement because he killed 3 of them when he killed himself in crap weather.

I don't collect "hero" badges or expect ATC to read my mind.

[co-joe]

XS you really crack me up sometimes. Doc..er Ilya, you too. But I'd at very least declare Pan pan or emergency if it were me. That way you don't end up in a hold while some ambulatory medevac for a lady with a sore tummy gets priority.

We had the whole left side of the BE3B go blank one night, marginal VFR and we asked for priority and turned around to cow town. All the right side instruments worked fine but we talked about it and decided pulling a shit hook and asking for priority was the right thing to do. Even a VFR aproach into a black hole is less safe with 3 blank EFIS/MFD's and managing risk is what we do. And hey, what if one stove quits now? What if the legs decide not to extend tonight? What if what if what if? Pretty sure you can't MEL the whole friggin dash....

[Captain X]

In the G1000 QRH guide there is no procedure i can find reagarding dealing with a Dual AHRS failure

[xsbank]

Co-Joe, all part of the service. You get what you pay for!

[swordfish]

What's a BE3B?

[GyvAir]

A 350.

[swordfish]

well, I lately drove a 350 but it was called a BE30

[co-joe]

Oh sorry. I forgot. They used to put BE3B on the type rating.

[PointyEngine]

Was that for some differentiation between the BE300 and BE350 before they were combined??

[GyvAir]

The way I understood it is that the second B in BE3B was to designate B300 (the "Super King Air 350) versus BE30 for the 300 (Super King Air 300).
As already pointed out, no longer relevant, as TC seems to have grouped them together now.

From outdated training policy letter:
Beech Aircraft Corp. BE30 Beech 300
Beech Aircraft Corp. BE3B Beech 350