Systems segregation

[deswalker]

Hi, I'm new on this forum and am wondering if someone could help me out with a fairly straightforward multiple choice question that I recently came across:

From an aircraft safety perspective, what would improving systems segregation achieve?

better maintenance access?
enhanced systems integrity?
longer component life?
an optimum system installation?


Thanks for your assistance!

 

[blueskiesup]

I vote enhanced system integrity. By seperating systems a localized failure doesn't affect both systems.

Once you consent to some concession,
you can never cancel it and put
things back the way they are.
---Howard Hughes---

 

[MintJulep]

The question is rather poorly written. Segregation is digital. Two systems are either segregated, or they are not. "Improved segregation" is non-sensical.

I vote for "none of the above".

Imagine:

System A is a safety-critical system. System B is not safety-critical.

If system A and system B are are segregated, then:

A failure of system A results in something bad happening.

A failure of system B does not.

If A and B are not segregated then:

A failure of system A results in something bad happening.

A failure of system B may casue a cascade failure of system A.

You need information regarding the reliability of the systems and access to the FMECA to correctly answer the question.

 

[rerig]

MintJulip,
Not entirely so.
A DC-10 has 2 segregated hydraulic systems. (Dual Systems)
An improved segregated system would be one where the 2 systems were physically separated a significant distance, so 1 penetration of the area by a sharp object didn't disable both systems. (Sioux City, Iowa)

 

[jsummerfield]

Segregated systems can enhance system integrity by reducing common mode failures. In this case, the system integrity might be mutually exclusive with operational integrity. Safety system components may shutdown a system that would otherwise be operational. The probabability is increased for eliminating an unsafe situation. This could mean increased downtime.

My background is the hydrocarbon processing industries such as offshore oil and gas, refining and petrochemical manufacturing. We want a balance. We segregate the shutdown system from regulatory process control. We implement triplicated or quad shutdown processors and multiple sensors and controls to increase operation on-time. A simplex or redundant voting shutdown system may be more safe; to shutdown the process on-deman. The triple or quad systems balance to protect from bad sensors, etc. that cause annecessary trips.

John