News reports and the blogosphere are buzzing with articles about Boeing’s Dreamliner problems, so I thought I would add my comments while trying to avoid beating the proverbial, “Dead Horse.” Perhaps a slightly different perspective might offer insight not commonly reported. For instance, I’m sure you’re all wondering what the 787 flight crews are doing now that they no longer have a ride. It might be interesting to note that most airlines staff 7 flight crews for each airplane in the fleet and an international crew consists of either 3 or 4 pilots, depending on the length of the flight. Not to worry—most union contracts cover this situation and the pilots are free of duty (except for training obligations) and are paid a monthly guarantee. Money is such a nasty subject—let’s talk about airplanes.
Of course, the Dreamliner’s problem has been identified as a faulty battery design that can cause an in-flight fire. However, there is no warning light in the cockpit that annunciates a battery fire. Therefore, the crew is left to identify the problem by the process of elimination and then deal with the situation. Place yourself in the captain’s seat at flight level 390 for this one. You just reported 30° West (mid Atlantic) to Gander Control and you’re two hours from Canada. The head mama (flight attendant) calls to inform you that something smells funky in the cabin. You tell her to check the galley ovens to see if food has spilled and is burning. She informs you that she’s not stupid and has already done that. Reserving your opinion, you ask her to check the lavatories to see if someone has disabled the smoke alarm in order to enjoy a cigar. She reiterates that she is not ignorant and the lavs are clear. She opines that the odor is acrid and smells like it might be of an electrical nature. You tell her to wake the relief pilot and send him to the cockpit.
The first officer digs out the procedures manual and opens it to the red tab labeled Fire and Smoke. You’ve already eliminated the usual suspects and the appropriate procedure is titled, “Smoke/Fumes of Electrical, Air Conditioning, or Unknown Source.” From training, you remember that this procedure is ten pages of agonizing trouble shooting. The relief pilot shows up and when he opens the cockpit door, acrid fumes permeate the flight deck.
There are two memory items in this emergency checklist to be accomplished before reading the procedure. Oxygen mask…on/100%, and Crew communications …establish. All three pilots don the full face smoke/oxygen mask and select 100% rather than diluted demand, then each selects interphone with their mic selector switch. At this point you establish who is going to fly the airplane and who is going to do the checklist. The relief pilot begins to read checklist items and the first officer accomplishes them and verifies while you fly the airplane.
This procedure systematically eliminates power from different portions of the electrical system until the smoke or fumes disappear. I’ll try to give you the big picture without getting too technical (bear in mind that I’m talking airliners in general, not specifically 787). Each engine has a generator and each generator powers an AC bus and a DC bus. In addition to that, there are left and right AC emergency busses and left and right DC emergency busses. Lastly there is a battery direct bus that provides emergency DC. Throughout the system, there are inverters that convert DC to AC and transformer rectifiers that convert AC to DC. Redundancy abounds.
Taking the power off a bus is simple, however you lose all electrical items powered by that bus and that can be a problem. Things like the autopilot, radios, instruments, the intercom you’re using to talk to each other, the anti-ice system if you’re in icing conditions, cabin pressurization, certain flight control functions, cockpit lights if it’s at night, and on and on. The point is, it’s imperative that someone concentrates entirely on flying the airplane and cannot become involved in the checklist other than to be informed as to what components are inoperative or need to be switched to another bus.
Sorry about the techno babble, but the point is, it’s a long and complicated procedure performed under the duress of putting out the fire and finding a place to land as soon as possible. The other point I want to make is, the battery direct bus (the source of the problem on the 787) is the last thing on the ten page checklist to be eliminated. In fact, the battery itself cannot be eliminated other than removing power from the charger. We can be thankful that this problem occurred and was identified without anyone being hurt. The Dreamliner will be flying and successful long after most of us have taken our last flight. It’s the nature of the business.