You'd think 777 would be a lucky number. Triple lucky, even. Yet for Boeing (NYSE: BA), the jumbo jet is proving quite a headache.

Yesterday, Boeing boasted of having sold two of its new 777-300ER aircraft to Angola's national carrier, TAAG, and of having persuaded it to sign up to purchase two more 777s at a later date. But no sooner had Boeing inked the deal (worth $544 million at list price, and potentially more than $1 billion), than what do you suppose happened?

Easy come, easy go
That's right -- a cancellation of 777s. Blaming the global financial crisis for causing "substantial changes in the aviation sector" (and the housing sector ... and the banking sector ... ), El Al Israel Airlines canceled its order for four 777s, nullifying both actual and potential revenue gains from the TAAG deal. Sharing Boeing's pain will be General Electric (NYSE: GE), which builds the giant turbofans that propel the 777 through the skies.

787: two-thirds as lucky?
The mixed 777 news comes just 24 hours after Boeing announced the latest twist in its long-running (too long, if you ask the suffering-in-silence customers at Delta (NYSE: DAL) and AMR (NYSE: AMR)) 787 Dreamliner saga. Citing component shortages at unidentified suppliers, and tardy completion of engineering and design changes that Boeing had requested, the company asked manufacturers to take an extra month to finish their work on fuselage segments for two aircraft. Boeing thinks this is better than accepting delivery of the faulty sections -- and having to fix the defects itself.

Now Boeing says it's built padding into its delivery schedule to account for such delays, and will not be thrown off schedule. The planes in question being 23rd and 24th in line for assembly, I suspect that's true. These delays should not, in and of themselves, prevent Boeing from making its first 787 deliveries this year, as promised. On the other hand, if this turns out to be just the first of a series of hiccups as Boeing rushes through the construction and FAA certification process, well ... 

Gambling on robots
But let's not close this article on a bum note. Rather, a note of optimism: Boeing confirmed Thursday that it has indeed begun building A160 "Hummingbird" robotic helicopters. Five aircraft will be built for testing purposes while Boeing awaits an actual order from the Pentagon. Will it materialize?

I sure hope so. It's about time some good luck came Boeing's way.

Meanwhile, Boeing's share price has turned around, and is moving back toward its 52-week high. How do you know when "the train has left the station," versus waiting to "buy on the dips?" Here's how. 

Fool contributor Rich Smith does not own shares of any company named above. The Motley Fool has a disclosure policy.