Preliminary investigations have identified hardware problems and corrupted software as possible causes of the recent failures of the Boeing Delta III and Lockheed Martin Titan IVB/Centaur boosters.
The second burn of the Boeing Delta III second stage lasted 1s, rather than the planned 2min 47s, stranding the Orion 3 communications satellite. Boeing says the guidance and software "operated properly" during the 4 May launch and cited "a hardware issue" in the premature shutdown of the second burn of the Pratt & Whitney RL-10.
Initial indications point to corrupted software as the cause of the Titan IVB failure on 30 April. During the first Centaur upper-stage burn, under the power of two Pratt & Whitney RL-10s, the stage deviated from its planned course and, in trying to correct the error, the software may have caused two later misfirings and the premature deployment of the Milstar 2.
The US Air Force has confirmed that the inertial upper stage (IUS) failure of a Titan IVB, launched on 10 April, was caused by incomplete separation of the first and second IUS stages.
US president Bill Clinton has requested a full report on the failures of the Lockheed Martin Titan 4Bs, the Athena 2 on 28 April and the Boeing Delta III. The US Congress House of Representatives Technical and Tactical Intelligence Subcommittee is investigating the launch failures.
The USAF has cancelled a Titan IVB launch planned for this month. Although the booster is not equipped with an IUS, or a Centaur upper stage, the launch is to be delayed until the completion of failure investigations. Flights of the Boeing Delta II, which does not carry an RL-10-class engine, have been cleared to continue, but a Delta II launch from Cape Canaveral, due on 15 May, has been delayed until next month.
Source: Flight International
