Right at the beginning of the adventure, the PCs are supposed to stop the engines of their shuttle from exploding. This requires two tech-use tests first at +0, then at -20, with 4 Degrees of Failure (failing by 30 or more) triggering an explosion.

A starting enginseer likely has an intelligence value somewhere in the low 40s. He has a combi-tool and probably either a servo-arm servitor or a straight +10 skill bonus.

Thus, he has a chance of about 40-45% to make the test and will blow up everyone on a roll of 70-75 or above.

If the group hasn't got an enginseer, the Operator will have to do. Assuming he's not busy with moving his vehicle against the orkish buggies, he might at least put his tech-use to good, well, use. Sooo… let's go for a 35 intelligence, no +10 and no tool. 15% chance of making the test, 45+ means blowing everyone up. Though it might be argued that he could simply use his comrade's Put That Out! to skip the whole thing, but presumably, that's not intended.

Considering that for many groups, this will be the second roll in the entire game, those chances seem rather harsh to me.

Well, operator got a MUI: so if he can get plugged, that's +10 right there. I suppose Operator comrade got one too, and might be able to help, so that's another +10%.

Or like you said, "Put that Out!" and done.

Good catch on the MIU. However, since the Enginseer has to pay for his Servitor to be able to assist with tech-use (as does the Medic with his aide), I assume comrades can't assist if they don't have a talent for it.

Well, that Put that out ability is one you must purchase; as for being able to assist the player in anything- then I suppose he can do that (to an extent really- turning the fire control on on the transport, ok: deactivating that ancient atomic with a minute n the clock? maybe not)

I say be brutal, kill a comrade if they botch it up on the drop.

No reason to let up, this isn't RT after all.

An alternate option: if no one in the group has good Tech-use, put an NPC on the field who does, such as an Enginseer (since there are shuttles landing, it would make sense some would be on station). Rather than making it into a tech-use challenge, make the challenge into a) the group noticing the issue, b) noticing the Enginseer, c) getting the Enginseer's attention, and the d) protecting the Enginseer while he starts repairs. This especially works if your group realizes it has not chance of fixing anything as complicated as a space shuttle engine.

After all, the engine won't explode for 60 rounds (and while you don't have to be specific with your PCs, when they notice it you can say something like "it looks unstable and is definitely is dangerous, but you think you have a minute or two till it goes critical). Instead of a Tech-use failure causing the explosion, making letting the Enginseer getting injured be the "explodes instantly" failure option, and as the Engineer takes a hit he slams into the engine during a critical operation, or something like that.