The tankage is indeed manufactured in Ukraine, but I believe the one used for this flight was shipped well before the current situation developed, even before the "Maidan" protests. The Antares' first stage tankage equipment is built by Yuzhnoye (Dnipropetrovsk), while the control system for analog Soyuz variants (U, FG) is made by Polysvit (Kharkov).

The NK-33 engines were manufactured in Samara (USSR, now part of the Russian Federation), but 40 years ago. Modificaton work (inspections, digital controllers and some part replacement) to transform them into AJ-26 was performed in Sacramento (CA, USA) and possibly the Stennis test facility in Missisippi.

I went through the video frame by frame several times and came to basically the same conclusion. I've attached screenshots of the two frames before the visible anomaly and two frames where something has clearly gone wrong.

My observations and speculation: It appears that the engine loses thrust and the plume becomes extremely rich, suggesting oxidizer starvation. The explosion occurs several frames later, then the rocket falls back with the first stage largely intact with the business end still burning. The explosion suggests that either the turbopump of the combustion chamber disintegrated, and combined with the apparent oxidizer starvation it suggests that the oxidizer side of the turbopump assembly suffered a reduction in flow rate followed by mechanical failure Based on the delay between apparent loss of oxidizer and explosion, my guess is a foreign object or contamination in the oxidizer.

We shall see. Different companies do failure boards with different degrees of success. There are lots of explicit and implicit pressures (PR, trying to preserve sunk costs, people who are *sure* what the cause is, political fallout, etc.) that must be ignored, since as Feynman said, "Mother Nature cannot be fooled". Orbital has had failure board failures in the past - they lost a mission due to a failed fairing, convened a failure board, implemented what they thought were enough fixes, then lost the next mission in the same manner.

The pressure on a company-employed failure board member could be enormously intense, even if self-induced. Suppose you were investigating the test stand explosion of the AJ-26. One possible outcome of the review board might be that these decade-old engines cannot be trusted. Do YOU want to be the person to tell your chairman your company made a mistake in picking these engines, it will need to refund the CRS contract, subject the company to public humiliation, stand down for four years, and lay off thousands of employees? The failure board folks know full well their recommendations have consequences, and it would require an inhuman level of dispassionate analysis for an employee to avoid even unconscious bias.

So no, I would not trust Frank Culbertson, or any Orbital employee, to lead the investigation. They have too much of an internal conflict of interest, despite their best intentions. I think the board must be led by, and primarily composed of, outsiders. To do otherwise is to expect too much of human beings.