Whiskey DeltaThank you very much for the info. We’ll catalog it as a “possible” aircraft instrument.
Whiskey DeltaInteresting. Is the 8 Day clock even an aircraft instrument? I tried Google but I couldn’t find anything.
Whiskey DeltaConversely, an evacuation can and often does result in injury to some passengers. You could argue that a completely unnecessary evacuation can likewise compromise the safety of the passengers, especially if you let them spill out onto an active taxiway!
All reports now completely retract the smoke claims. It was an error message and smell that prompted the pilots to divert (prudent move) and eventually evacuate (over reaction).
Is it better to risk a potential fire given system warnings and odors then risk a possible injury with an evacuation? Nope. Evacuate. By the time the crew would get their 3rd or 4th indication after ignoring the first 2 (warnings and odor) it could very well be too late to insure a safe evacuation for all passengers and crew.
Whiskey DeltaWhat a wonderful opportunity. I was forced to cancel a recent planned trip to Washington DC, and these pictures add to my general sense of frustration at not being able to be there.
It is interesting to think what the modifications to the B747 are, apart from the visible ones. It looks like a 100 or 200 to me.
According to wikipedia it’s a former AA 747-100.
http://en.wikipedia.org/wiki/Shuttle_Carrier_Aircraft
Great stuff.
Can I ask which company you’re with and which plane you’re flying?
EMB-145 for ExpressJet Airlines
Whiskey DeltaSorry, I should have been more specific. The cockpit side view windows have the inscription.
Whiskey DeltaThey’re the same as you said Gerry. The side view windows even say “EMB-120, EMB-145” on them.
Whiskey DeltaI don’t think this information/article has been posted yet so apologies if it has.
A bit over dramatic by using the name “Scarebus” but a lot of the other mentioned system failures was new to me. Sounds like that 1 engine knocked out a lot of systems. The first comparison that came to mind was United 234. A single uncontained engine failure leading to enough systems be damaged that the airplane was nearly unflyable. An amazing test of skill for this Qantas crew.
1 Massive fuel leak in the left mid fuel tank (there are 11 tanks, including in the horizontal stabiliser on the tail)
2 Massive fuel leak in the left inner fuel tank
3 A hole on the flap fairing big enough to climb through
4 The aft gallery in the fuel system failed, preventing many fuel transfer functions
5 Problem jettisoning fuel
6 Massive hole in the upper wing surface
7 Partial failure of leading edge slats
8 Partial failure of speed brakes/ground spoilers
9 Shrapnel damage to the flaps
10 Total loss of all hydraulic fluid in one of the jet’s two systems
11 Manual extension of landing gear
12 Loss of one generator and associated systems
13 Loss of brake anti-skid system
14 No.1 engine could not be shut down in the usual way after landing because of major damage to systems
15 No.1 engine could not be shut down using the fire switch, which meant fire extinguishers would not work on that engine
16 ECAM (electronic centralised aircraft monitor) warnings about the major fuel imbalance (because of fuel leaks on left side) could not be fixed with cross-feeding
17 Fuel was trapped in the trim tank (in the tail)creating a balance problem for landing
18 Left wing forward spar penetrated by debris
Whiskey DeltaGeez, they’ll never get to delivering this thing to customers. I thought the A380 delays were bad but Boeing is trying to be #1 in aircraft sales, delays and cancelled orders all in one shot.
Whiskey DeltaJust make a PA that the cockpit seatbelt position indication system had indicated that passengers aren’t complying and we’ll be stopping until the offenders comply.
Whiskey DeltaThere are certain phones that have noticible affect on communications. Nokia and iPhones are 2 that I can think of that, if left on, can be heard over the pilot headsets making clicking or sweeping noises while they roam. Does it have any impact on navigation or other system in a negative way? Beats me, I haven’t seen it. But if phones can be heard audiably over the intercom what may they be doing that can’t be heard? Why take the chance? The phone is worthless above a few thousand feet anyway so just turn it off.
Whiskey DeltaLike the FARs turned out to say, Vmcg must be established with “maximum available takeoff power on the operating engines”. So in case of paper derate, either Vmcg is unchanged or else the full thrust is made unavailable even in emergency.
That is incorrect. The certification says Vmcg is based on max thrust available (ie pushing the levers full forward), not based on the calculated reduced thrust setting. In a reduced thrust takeoff, maximum thrust is always available and that is what Vmcg is based on.
Back to the original intent of this thread, why would a manufacturer/operate limit the capability of their aircraft by eliminating the ability to increase thrust to account for variations in weight, runway length, terrain clearance, temperature, runway elevation, etc.? I can say from experience that these are all things that have lead to needing to use full TO power rather than reduced thrust. Your original statement would have led to us removing gas, passengers or payload because you believe manufacturers should install smaller engines because that is all the thrust we use in 80% of takeoffs. Being in the business of moving people and payload, airlines want maximize those even when conditions change (weight, runway length, terrain clearance, temperature, etc.).
Whiskey DeltaLooking for the FAR definition/certification criteria for Vmcg I came to this.
(f) At the option of the applicant, to comply with the requirements of §23.51(c)(1), VMCG may be determined. VMCG is the minimum control speed on the ground, and is the calibrated airspeed during the takeoff run at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the airplane using the rudder control alone (without the use of nosewheel steering), as limited by 150 pounds of force, and using the lateral control to the extent of keeping the wings level to enable the takeoff to be safely continued. In the determination of VMCG, assuming that the path of the airplane accelerating with all engines operating is along the centerline of the runway, its path from the point at which the critical engine is made inoperative to the point at which recovery to a direction parallel to the centerline is completed may not deviate more than 30 feet laterally from the centerline at any point. VMCG must be established with —
(1) The airplane in each takeoff configuration or, at the option of the applicant, in the most critical takeoff configuration;
(2) Maximum available takeoff power on the operating engines;
(3) The most unfavorable center of gravity;
(4) The airplane trimmed for takeoff; and
(5) The most unfavorable weight in the range of takeoff weights.
And from the charts I’ve referenced it is based on temperature and weight.
So, suppose that a takeoff thrust is selected, lower than the available emergency thrust, Vmcg is lowered based on the selected takeoff thrust and V1 is lowered accordingly, so that it is bigger than Vmcg for selected takeoff thrust, but lower than what Vmcg had been for available emergency thrust.
And right after V1 – still below what Vmcg had been for available emergency thrust – one engine fails.
What thrust will then be applied by the remaining engine – the selected takeoff thrust, or the available emergency thrust?
None of your situation matters as Vmcg is based on full power being used in the operating engine(s).
So what’s your point again? You want smaller engines installed on all airplanes because reduced thrust takeoffs are an indication that those big fancy engines aren’t really needed? This is one of the most bizarre aviation ideas ever.
Whiskey DeltaVmcg is estimated for the case of one engine out and the other providing full thrust near V1. Which is an emergency situation to begin with. So how can Vmcg be changed for derate if the derated thrust would be exceeded in emergency (and take the airplane right off the side of runway at high speed)?
Vmcg is estimated base on weight and selected takeoff thrust. The definition of Vmcg is the minimum speed an aircraft can maintain directional control on the runway using rudder only at takeoff thrust. On a derated takeoff all v-speeds are calculated based on that selected takeoff thrust, the current weight of the aircraft and pressure altitude, that includes Vmcg if an aircraft has one. For a given weight the value of all v-speeds will vary depending on the selected takeoff thrust setting and temp/altitude.
The use of the remaining available thrust after an engine loss has no impact on Vmcg. Vmcg can’t exceed V1 and any emergency situation prior to V1 requires aborting the takeoff and not flying. In other words, once the takeoff is aborted that excessive thrust will never be applied no matter what takeoff thrust setting that was selected.
That excess thrust is available to allow variations in takeoff weights, runway lengths, runway slope, terrain, etc. You’re suggesting that manufacturers eliminate that excessive power rather than permit derated takeoffs or they put all their eggs in 1 or 2 baskets by having 1 or 2 engines provide a majority of the thrust with others providing less? Operators then can kiss goodbye the cost savings of being able to derate a takeoff should it be needed or enjoying increased payload or operating at high altitude airports or terrain intensive regions, etc.
Whiskey DeltaDerated takeoffs change V1, VR, V2, second segment climbs, etc. Should Vmcg be calculated it would change as well. The same could be said for Min vs. Max weight takeoffs. I don’t know what you’re implying with your question.
Whiskey DeltaBut not worse than losing one of the two engines on a twin.
Right, so if it’s not worse than a scenario on twin engine than why is it a concern on an aircraft with more engines? By your suggestion, having 1 or 2 particular engines with a higher thrust rating is a recipe for worse scenario should they be the ones that fail.
It would be no different that having 1 of 4 backup computers be responsible for 80% of the aircraft systems. There would be a 75% chance that the other, less critical, computers would fail increasing your odds of having less of a performance impact when one of them fail. Still, there is a 25% chance that the computer responsible for most of your systems would fail leaving you in a worse position than if the load had been shared equally across all 4 computers.
A lot of planes do add software to flight computers, and have paper derate of MTOW and engine thrust without actual physical alterations of structure or engines.
You’ve answered your own question and probably don’t realize it. Derated takeoffs extend the life of the engine but don’t change the amount of available thrust in an emergency situation. By your original post you’d rather just seen smaller engines. Well that would give you the same effect of a derated takeoff 100% of the time but it would also permanently lower your amount of available thrust should you need it in an emergency (ie An engine loss).
Engines derated on paper have the same size, weight and drag as engines providing their full rated thrust. So why do lower MTOW variants of airliners not have physically smaller engines installed?
Engine size (or lack of) isn’t an indication of engine differences. There could be different fuel flow controllers, ignition systems, defusers, pumps, mounts, etc. installed. Look at the variation of performance on the CFM series for the 737NG.
http://en.wikipedia.org/wiki/CFM_International_CFM56#CFM56-7_series
Because it all fits into the same nacelle the amount of parts needing to be stocked is significantly for those carriers who operate more than 1 variation. Not to mention that there would be less engineering involved with engines that are the same size than modifying an airframe to handle the different aerodynamics resulting from having physically different engines installed on different aircraft versions.
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