CRJ900 IRS high drift rate

[dcoded]

Hi

we are experiencing problems on both IRS units on one particular aircraft individual in our fleet.
aircraft is around 2 years old and the IRS is drifting between 4-8NM per hour flying north/south I in the northern hemisphere.
last days we have started our journeys from around N54, and needed to do full alignment on the turnarounds due to IRS FMS disagree.

any takes on this?
what baffles me is that both IRS drift quite a lot.
imminent failure approaching?

[vickers vanguard]

Hi

we are experiencing problems on both IRS units on one particular aircraft individual in our fleet.
aircraft is around 2 years old and the IRS is drifting between 4-8NM per hour flying north/south I in the northern hemisphere.
last days we have started our journeys from around N54, and needed to do full alignment on the turnarounds due to IRS FMS disagree.

any takes on this?
what baffles me is that both IRS drift quite a lot.
imminent failure approaching?


wayyyyy too much drift for a 2 years old airplane. The RC FMS 4200 or the 6000 series will usually post an FMS-IRS disagree when you have 2.5 nm of drift in the first 30 mins of flight, and there after, if the drift is more than 2.5nm per hour of flight...those are typical numbers.

[Eric Janson]

Hi

we are experiencing problems on both IRS units on one particular aircraft individual in our fleet.
aircraft is around 2 years old and the IRS is drifting between 4-8NM per hour flying north/south I in the northern hemisphere.
last days we have started our journeys from around N54, and needed to do full alignment on the turnarounds due to IRS FMS disagree.

any takes on this?
what baffles me is that both IRS drift quite a lot.
imminent failure approaching?

I've experienced a large drift on 1 IRS on a different Type.
An investigation found this IRS had a different part number and shouldn't have been installed in that airframe.

This should be the first thing to check.