Mobile Command Center Repair for Rancho Santa Margarita Agencies

Strip the graphics off one of these and what you have is a conventional body with a steel structure running through it from the roof to the frame. That structure exists for one reason: to hold a mast up in wind. Everything else in the build, the racks, the slide, the generator and the workstations, is arranged around it and around the cable chases feeding the roof.

That single fact organizes the whole repair. Body damage on a command unit is straightforward. What is not straightforward is anything that shares a load path with the tower or a penetration with the roof, because those items were engineered as a system by the builder and they have to go back as one.

• Mast tower: welded steel from roof to frame outriggers
• Roof: a dome curb, antenna mounts and sealed cable penetrations
• One body side: a large conference slide opening
• Floor: a line of rack mounts along one wall

A mast at full extension is a lever, and wind on the head arrives at the base as a bending moment. The base plate is welded to frame outriggers and the tower passes through a hole in the roof, sealed with a boot or a flanged collar. That moment only exists while the mast is up, so the welds see a few dozen heavy cycles a year rather than a continuous load.

Slow cycling produces slow cracks, and they start at the base plate weld toes where the section changes. We dye check the base plate on every command unit we open up, and we look at the roof collar at the same time, because a tower that has been flexing has usually been working the collar seal as well.

A one point two metre auto acquire dome with its positioner is heavy and it sits on a curb with a long sealed flange. The roof underneath flexes over every expansion joint on the freeway. The dome does not, because it is stiff and heavy, so the flange has to absorb the difference and it eventually stops doing that.

Water then enters slowly at the flange and the laminated roof panel begins to separate from its core in a ring around the curb. From the roof it looks like nothing. From inside, a ceiling panel starts to sound hollow when tapped. We map the delaminated area with a tap test and moisture readings before deciding whether it is a local repair or a panel.

The conference room is often the biggest slide we see in this family. It carries a table, seating, monitors on arms bolted to the room framing and sometimes a whiteboard wall, all supported at the inner edge by through frame hydraulics. Physics does the rest: the outboard corners settle first.

What makes command units different is that the room sits retracted for months between deployments, so the wiper and bulb seals take a compression set and lose their memory. Cycle the room twenty times at an incident and the seal never recovers. We re-support and square the room, then replace the seals, because sealing a room that is not square is a repair with a short life.

1. Run the room out and measure the gap at all four corners
2. Load the floor at the outboard edge and measure again
3. Re-support the room and correct the geometry first
4. Replace wiper and bulb seals only after the room is square

A loaded nineteen inch rack is four to six hundred pounds standing in a footprint about two feet square, and command builds regularly put two or three of them in a row along one wall. That is a line of concentrated loads on a floor designed for distributed weight, and the deflection between cross members is enough to make a rack rock at the top even when the bolts are tight.

A rocking rack then works its own mounts, and a loose rack in a moving vehicle is a safety issue as much as a structural one. We map the cross members, add steel under the floor where the racks land, and fit the bases to that steel rather than to plywood. Where the rack line straddles a member we relocate the mounts rather than accept a compromise.

Command units carry a diesel set large enough to run the whole build, and it lives in a compartment engineered as much for quiet as for cooling. Restricting the air path keeps the noise down at a scene and it also keeps the heat in. At a monthly test that is irrelevant. At a twelve hour deployment in August it is not.

What we find is cooked bulkhead insulation, hardened sealant around the exhaust penetration and cracked mounts, because thermal cycling has been added on top of vibration. We rebuild the bulkhead with material rated for the temperature, reseal the penetration and rebuild the mounts, then check the compartment air path rather than assuming the original arrangement was adequate.

There is no mobile repair capability here and no roadside program, and on a rated mast tower that is not a limitation anybody should want lifted. Tower welding, roof laminate work and slide geometry all need the building. Units arrive from Rancho Santa Margarita on the 241 to the 91 with the mast stowed and pinned.

Tower, roof, slide and floor work bills at $210 per hour with body supplies at $5 per body hour. Generator compartment, shore inlet and rack circuit work bills at $260. Fault tracing across a build with three power sources bills at $285 per hour with a one hour minimum, credited against an authorized repair. A written estimate is $150 on the same terms.

A 40 foot command unit is the largest thing in this family and it fits comfortably: twelve feet six to thirteen feet over the dome and mast head, well inside our sixteen foot bay doors, and it paints whole in the sixty foot booth. It goes into a bay with side clearance because the conference slide has to be cycled. We need the mast in the stowed and pinned condition at drop off, the mast maker's service data if tower welding is in scope, and the radios either removed or the racks locked and keyed.