Qatar is buying four US refuelling tankers. The notification sent to Congress on Thursday lists "four installed engines" for the four of them. The aircraft needs two!!! Boeing builds one kind of KC-46 and it has two engines. Whatever Qatar ends up flying will have the right number. The notification the State Department published on Thursday covers a possible sale worth 4.5 billion dollars, of up to four KC-46As. It lists eight engines, four installed and four spare. Four installed engines shared across four aircraft is one each. The same arithmetic went to Congress in 2019. That notification covered four KC-46s for Japan and six engines, two of them spares. Four installed, four aircraft, one each again. That same document states that every KC-46 is powered by two PW4062 turbofans. Israel's notification in 2020 did it correctly. Eight aircraft, seventeen engines, sixteen installed and one spare. Every other line in Qatar's list checks out. Ten radar warning receivers, four installed, one per aircraft. Fifteen laser transmitter assemblies, twelve installed, three per aircraft, which is the published fit. The engine line is the only one that fails, and it failed the same way seven years ago. The installed and spare breakdown is how Congress reads whether a buyer can keep its aircraft flying. Four tankers with four spare engines can absorb a failure. Four tankers with none cannot. On this notification that breakdown describes something that cannot be built. Bloomberg, Defense News, Aerotime and at least six trade outlets carried the sale on Thursday and Friday. One of them, defence-blog, printed the four-installed line near the top and the two-engine specification further down the same article. Congress gets thirty days to review a sale like this to Qatar, running from the day it receives the certification. Nothing published so far says which day that was.