I prepared the Maintainability criteria document for the Agusta 129 and I was responsible for the same material on the Agusta portion of the EH-101. In the case of the A-129 the helicopter was already designed so there was no input into design modification to maximize the design for maintainability. As such the numbers that we calculated for the A-129 were quite high due to the lack of design for maintainability. This document was specifically for the Italian Army to show the ease of maintenance and for provisioning of manpower and spares. The department manager decreased all of the numbers in order to make it look good. I can only assume that when the helicopter went into service they had to increase their manpower and spares provisioning.
When I prepared the document for the EH-101 the same thing happened regarding the decreasing of the numbers. The manager used numbers from the ASH-3D that were not fully recognized as being truly representative of the actual helicopter MMH/FH. Here again there was a significant effect on the maintenance structure of the operators.
The US Army approaches it backwards. They do a bit of war gaming to determine the battle group strength necessary to repel an enemy force. From that they determine the number of attack helicopter groups and from that they determine the number of helicopters in each battle group. They then determine the availability or the helicopters in each group. In other words if they determine that if there are ten helicopters in each group they must have eight available for mission dispatch. This means 80% availability.
This availability figure is written into the contract and the R&M group at the contractor must extrapolate what the reliability and maintainability must be for the helicopter at the top level. From this they apportion the R&M characteristics for each system and they then determine the R&M characteristics for major system components and this is written into the contracts for the vendors.
Starting at the bottom each part and each subsystem as well as the systems must show compliance with the contractual figures in order to meet the availability requirements set down by the Army. In other words the Army provides a meaningless figure to the contractor and also provides the procedures to determine the necessary R&M figures. The contractor then using these criteria will start the big lie and impose these lies on the subcontractors who in turn state that they will meet these requirements. In this way when all of the parts are added into the system the contractor is guaranteed to meet the Army’s requirements.
To make matters worse eighteen months later the contractor must show reliability growth. Since at that time the design is frozen there is no possibility to change the design to improve it. So, the contractor refers to official databases and extracts better numbers for the various items showing the Army that they have in fact improved the design.
When the helicopter is fielded it performs poorly consuming parts at an alarming rate and using more maintenance personnel than originally required. In some cases the helicopter is so complex that the Army technicians can’t maintain it and contractors are brought into the mix. The Army just waits until the next meeting of congress and asks for a higher appropriation in order to meet their operational commitment.
Does this sound familiar to those of you that were in the military?
To: Cyclic Hotline
The determination of MMH/FH on US Military contracts is stipulated to reflect only active tool time on the subject equipment. It does not include the time it takes to get the replacement part, the time it takes to get a special tool, the time it takes to get access equipment (check stands) or other items that do not directly relate to the repair procedure.
It does include the time to gain access, the time to locate the defect, the time it takes to isolate the defect, the time to remove the element, the time it takes to replace the element, the time it takes to determine the efficacy of the repair, the time to clean the area, the time it takes to secure the area (close the cowling or replace the access panel(s).
It is implied by the military organization that they will factor in all of the logistics elements related to the specific repair. However the calculations made by the contractor relative to MMH/FH are what the operator sees and it will appear that they can never meet these requirements. What the operator must look at are the availability figures specified by the contract as this figure more truly reflects what is happening. In most cases it take years to meet this figure if in fact it is ever met.
The UK uses these same procedures which were adapted in 1983. This document was extracted with minimal changes from the US standards and is reflected in Defense Standard 00-41 (PART 1) / Issue 1 MOD PRACTICES AND PROCEDURES FOR RELIABILITY AND MAINTAINABILITY.
I can’t say that the UK handles it any differently than they do in the US but it seems that the Merlin indicates that they do.