Selective RSL - Multiple FMs

This article describes how to use the Selective RSL functionality when multiple Specs on FLOCs (and Equipment) are involved, and how the resulting Strategies can cover multiple Failure Modes (FMs) at once.

This example builds on Selecting RSL Tasks Based on Specs - Background and Selecting RSL Tasks Based on Specs - Details, which introduce the single-Spec version of this example. Here, we extend it to three Specs and six Failure Modes.

FLOC and Equipment Specs

In this example, three Specs are used on a Control valve. Each Spec can have the value YES, NO, or blank:

ECS SEVERE SERVICE
ECS TEMPERATURE OVER 400
ECS OVERHAUL REPLACEMENT

With three Specs and two possible values each (YES/NO), there are 8 possible combinations.

Note

You cannot steer an RSl based on a blank Spec. Using multiple Specs, each with multiple possible values, can quickly produce a large number of combinations to consider when setting up a Selective RSL.

To illustrate the effect of the Strategies, we created 8 FLOCs — one for each combination:

Table showing ECS service requirements with highlighted entries for severe service and temperature.

The picture below shows how the Specs appear in IMS for three of these demo FLOCs: 10FRC-S0-T0-R0, 10FRC-S1-T0-R0, and 10FRC-S1-T1-R1.

Control valve specifications showing various ECS conditions and their values across three FLOCs..

Before setting up the Selective RSL, we recommend mapping out the story line from Location type/Equipment group to the relevant FMs and their applicable maintenance tasks. This gives a clear view of how the different Specs affect each FM scenario and its tasks.

For the Control valves in this example, the Failure Modes are:

ACTUATOR FAILURE
AIR FILTER FAILURE
CV FAILURE
CV GLAND LEAKAGE
CV PASSING
CV POSITIONER FAILURE

Based on these FMs, we recommend defining the applicable tasks first as these form the basis for the RSL structure used below.

Table detailing ECS service requirements and maintenance actions for various failures.

Each Spec then steers which of these tasks apply — and with what content — across all six FMs.

Effect of Spec on Failure Modes and Tasks

As shown in Selecting RSL Tasks Based on Specs - Details, a single Spec (ECS OVERHAUL REPLACEMENT) can drive whether the Actuator Failure FM gets a Cleaning and Stroke test every 4 years or every 10 years. The same principle applies here, just with three Specs steering tasks across all six FMs instead of one Spec steering one FM.

Set up Selective RSL

With the tasks defined, we set up the eight Strategies on the Selective RSL. Each Strategy bundles the tasks that apply to all six FMs for one combination of the three Specs.

Strategy	Severe Service	Tover 400	Overhaul Repl
1	No	No	No

Strategy 1 on the Selective RSL.

Strategy	Severe Service	Tover 400	Overhaul Repl
2	No	No	Yes

Strategy 2 on the Selective RSL.

Strategy	Severe Service	Tover 400	Overhaul Repl
3	No	Yes	No

Strategy 3 on the Selective RSL.

Strategy	Severe Service	Tover 400	Overhaul Repl
4	Yes	No	No

Strategy 4 on the Selective RSL.

Strategy	Severe Service	Tover 400	Overhaul Repl
5	Yes	No	Yes

Strategy 5 on the Selective RSL.

Strategy	Severe Service	Tover 400	Overhaul Repl
6	Yes	Yes	No

Strategy 6 on the Selective RSL.

Strategy	Severe Service	Tover 400	Overhaul Repl
7	No	Yes	Yes

Strategy 7 on the Selective RSL.

Strategy	Severe Service	Tover 400	Overhaul Repl
8	Yes	Yes	Yes

Strategy 8 on the Selective RSL.

Assign FLOCs to the Strategy

Once you set up the Selective RSL Strategies and create the FLOCs with Specs, you can assign the Selective RSL strategies. The video below shows the created Strategies and the FLOCs with their Specs, and walks through the assignment steps:

In the end, 8 different strategies are applied through one RSL, driven by the Spec values on each FLOC. The grid below shows the RSL and Strategies connected to the relevant FLOCs:

FLOC list displaying the RSL and Strategies connected to the relevant FLOCs..