Lockheed happy with ECO changeout

by Chris Bergin

Lockheed Martin technicians are in the final stages of closing out work on the aft of ET-119, following the changeout of the tank’s ECO (Engine Cut Off) sensors.

The tank is currently in the horizontal position, with TPS (Thermal Protection System) foam being re-applied to its aft dome section, ahead of being stacked and mated with the two SRBs (Solid Rocket Boosters) that will make up STS-121.

‘So far the work is going pretty well. The key to any success is the pre-work, the planning and reviewing all the paper,’ Jim Feeley, ET launch integration senior manager, in an address to Michoud workers in New Orleans. ‘I attribute our progress to the hard work of the team involved.’

The replacement and leak testing of the tank took place a few days ago, after the manhole – used to access inside of the tank – was reinstalled. The Lockheed team had to wait for the replacement work to the vent and relief valve at the top of the tank to be completed – after tests showed it was ‘leaking slightly’.

The vent valve controls tank pressure during propellant loading – and acts as a safeguard against over pressurization.

‘We always do the aft TPS closeout when the tank is horizontal at Michoud so we’re following that same process at KSC,’ Feeley said in reference to waiting for the tank to be moved back to the horizontal.


Some extra work had to be done to the top of the tank, after technicians removed duct tape over a light stand cord to reposition the fixture for better viewing of the vent/relief valve inadvertently tugged on the power cord pulled the fixture over, first hitting the guardrail, then the composite nosecone and forward ogive foam.

The light fixture made several small indentations, one approximately seven inches long in the foam. TPS repair to that section has now been completed.

‘Obviously, we didn’t plan for a light falling over, but our contingency planning enabled us to respond immediately,’ Feeley said, while noting the work on the vent/relief valve was actually more complex than the ECO changeout. ‘There are more systems to address.’

Leak checks on the valve have been completed – with monitoring of the system during a potential tanking test set to confirm the successful changeout, as well as the new ECO sensors now inside ET-119.

Currently, ET-119 is due for stacking on April 26, as Discovery’s rollout grows ever-nearer. However, July’s launch target is still in doubt, especially with a number of concerns over the wind tunnel test results – with one major red flag coming to light over the last 24 hours (report to come).

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