Mr. Mercat always carries duct tape. We were on a Lufthansa flight in 2016 when the air conditioning started leaking. The attendant said , ah, ya, it happens sometimes. It will stop soon. But meanwhile several passengers were getting quite wet. Mr. M passed them some duct tape and the taped the area shut. We got free champagne.
Mr. GG2 who used to work for Boeing building the interior s fixed the drink cart and an oven in the kitchen on one flight and they moved him to first class. :-)