Attitude Indicator and Stalls.

luvflyin

Touchdown! Greaser!
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Luvflyin
I posted this, "As I recall, the only thing that could have resolved the problem was the Attitude Indicator. Put the wings so many bar widths above the horizon and hold it there regardless of what the other instruments were saying," in a thread about auto pilots that led to the Air France accident. Didn't get any response and I want to know, so starting this thread about it in particular. Youse big iron guys, is this part of emergency training? When everything else goes nips up and starts lying to you, just hold an 'attitude.'
 
N1?? What exactly are the words in ANU?
N1 is the speed of the fan (low-speed spool) in percentage. It is the primary power indication for each engine. We also have an indication of N2 which is the speed of the high-speed or core spool. N2 is not generally used for setting power settings.

ANU is Aircraft Nose Up. Pitch attitudes below the horizon are AND.
 
Ok...pitch plus power still allows you to stay in the air because you’re not clueless as to what your airplane is doing.

Yeah. Gotcha.
Flaps extended ... 10° ANU and 80% N1
Flaps up ... 4° ANU and 75% N1
That is pitch plus power
 
It is part of the Airspeed Unreliable checklist on the 737 as a memory item.

Flaps extended ... 10° ANU and 80% N1
Flaps up ... 4° ANU and 75% N1
What about power? If the engine instruments aren’t passing the logic check like what happened to Air Florida into the Potomac, is there a default setting? Like say 4” short of full throttle or something like that?
 
What about power? If the engine instruments aren’t passing the logic check like what happened to Air Florida into the Potomac, is there a default setting? Like say 4” short of full throttle or something like that?
No. Nothing like that.

Air Florida was using EPR (Engine Pressure Ratio) which can be affected by things like probes icing over. N1, unless the transmitter fails, will give a true representation of thrust.

Air Florida crashed because those guys had no idea how to do winter operations.
 
What about power? If the engine instruments aren’t passing the logic check like what happened to Air Florida into the Potomac, is there a default setting? Like say 4” short of full throttle or something like that?
If the problem was a failure in the engine instrumentation then we'd set the power to achieve the desired airspeed. We have three independent airspeed indicating systems.

I've had an unreliable airspeed once in the 737. It took about five seconds to compare the three readings and determine which one was bad.
 
N1 is the speed of the fan (low-speed spool) in percentage. It is the primary power indication for each engine. We also have an indication of N2 which is the speed of the high-speed or core spool. N2 is not generally used for setting power settings.

ANU is Aircraft Nose Up. Pitch attitudes below the horizon are AND.
We always used EPR for power settings.
 
Air Florida crashed because those guys had no idea how to do winter operations.
Well, the EPR probes were full of deice fluid. Then, the copilot, who was making the takeoff, was complaining to the Captain that the thrust levers didn't "feel right" (not pushed far enough forward), but in ambiguous language. In response, the captain referenced the EPR gauges and insisted the thrust was correctly set. See my post in the Marine crash thread re: the conservative response to challenge. They ought to have aborted to find the cause of their disagreement.
 
Well, the EPR probes were full of deice fluid. Then, the copilot, who was making the takeoff, was complaining to the Captain that the thrust levers didn't "feel right" (not pushed far enough forward), but in ambiguous language. In response, the captain referenced the EPR gauges and insisted the thrust was correctly set. See my post in the Marine crash thread re: the conservative response to challenge. They ought to have aborted to find the cause of their disagreement.

After the AF crash airlines began adding N1 setting to the TOLD card in addition to target EPR. Trust, but verify.
 
Well, the EPR probes were full of deice fluid. Then, the copilot, who was making the takeoff, was complaining to the Captain that the thrust levers didn't "feel right" (not pushed far enough forward), but in ambiguous language. In response, the captain referenced the EPR gauges and insisted the thrust was correctly set. See my post in the Marine crash thread re: the conservative response to challenge. They ought to have aborted to find the cause of their disagreement.
It wasn't deice fluid on the probes, it was ice. These guys used reverse on the ground to help the pushback (throwing ice and slush forward into the engine), they never turned the engine anti-ice on in heavy snow and freezing temperatures, they got close to an aircraft in front of them in an attempt to melt the ice off their own leading edges (which had the opposite effect of melting the snow and having it refreeze on the LE), then they attempted to take off with snow and ice adhering to the wing and finally they either (a) didn't reject the takeoff or (b) push the thrust levers up when they got the stick shaker.
 
It wasn't deice fluid on the probes, it was ice.
You don't know that for a fact. We do know that deicing personnel were observed shining their pressure washers onto inlet cowls where the EPR probes were located, IIRC. As to some of your other comments, after every accident those with an agenda start citing their pet causes in "Never waste a crisis," fashion. EPR probes can fail and aircraft can usually takeoff with some contamination on the wings, a lot of others did that day. You wouldn't blame the crew if it was simply a mechanical EPR indication failure, I bet, using your same logic. But the result would have still been a crash.You will never convince me the real root cause wasn't the lack of communication between the pilots regarding the true nature of the copilot's concern. That and, as you did mention, not hitting the iron stops with the thrust levers when faced with stall warnings. That isn't necessarily emphasized enough during training, or at least wasn't back then.
 
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No. Nothing like that.

Air Florida was using EPR (Engine Pressure Ratio) which can be affected by things like probes icing over. N1, unless the transmitter fails, will give a true representation of thrust.

Air Florida crashed because those guys had no idea how to do winter operations.

Is N1 something
After the AF crash airlines began adding N1 setting to the TOLD card in addition to target EPR. Trust, but verify.

I was wondering if they had that N1 thing back then. Guess so. What exactly is it?
 
Is N1 something


I was wondering if they had that N1 thing back then. Guess so. What exactly is it?

N1 refers to turbine rpm in percent. And yes, they had it on the 737-200 (P&W JT-8D).

From Wikipedia:

The JT8D is an axial-flow front turbofan engine incorporating dual-spool design. There are two coaxially-mounted independent rotating assemblies: one rotating assembly for the low pressure compressor (LPC) which consists of the first six stages (i.e. six pairs of rotating and stator blades, including the first two stages which are for the bypass turbofan), driven by the second (downstream) turbine (which consists of three stages); and a second rotating assembly for the high-pressure compressor (HPC) section, which has seven stages. The high-pressure compressor is driven by the first (upstream) turbine, which has a single stage.

The front-mounted bypass fan has two stages. The annular discharge duct for the bypass fan runs along the full length of the engine, so that both the fan air and exhaust gases can exit through the same nozzle. This arrangement allows some noise attenuation, in that the still-hot fast-moving turbine exhaust is shrouded in much-cooler and slower-moving air (from the bypass fan) before interacting with ambient air. Thus the JT8D noise levels were significantly reduced from previous non-turbofan engines, although the low bypass ratio meant that, compared to subsequently developed turbofans, high noise levels were still produced.

Eight models comprise the JT8D standard engine family, covering the thrust range from 12,250 to 17,400 pounds-force (62 to 77 kN) and power 727, 737-100/200, and DC-9 aircraft. More than 14,000 JT8D engines have been produced, totaling more than one-half billion hours of service with more than 350 operators making it the most popular of all low-bypass turbofan engines ever produced.

Within the fan inlet case, there are anti-icing air bosses and probes to sense the inlet pressure and temperature. Similar units exist throughout the engine to check temperatures and pressures.

At the 13th (i.e. the final) compressor stage, air is bled out and used for anti-icing. The amount is controlled by the Pressure Ratio Bleed Control sense signal (PRBC). The diffuser case at the aft end of the compressor houses the 13th stage. Its increasing cross-sectional area allows the compressed air to slow down before entering one of the engine's nine burner cans. Again, there are two bosses to extract 13th stage air for anti-icing, de-icing of fuel, and airframe (cabin pressurization) use. Not all the compressed air enters the burner cans at the fuel-ignition point; some bypasses the can completely and cools the first turbine stage, and some is gradually introduced into the burner can's perimeter in such a way that the burning fuel is held near the can's centerline.

There are nine combustion chambers positioned in a can-annular arrangement. Each chamber has three air inlet hole sizes: the smallest is for cooling, the medium is for burning and the large for forming an air blanket.

17eec025258a08e28fc8034893f87556.jpg

The blue area is N1, and the yellow area is N2.

When calculating TO thrust for a certain runway using temperature and wind, plus any runway contamination (water, slush, ice) an EPR number is derived, plus a target N1 number to crosscheck the EPR setting.
 
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The CFMs (GE) don't have EPR like the Pratts did. Can't remember if Rolls engines have EPR.

Doesn't really matter, though. The "top gauge" is the primary for setting power.

RR RB-211's were "triple spool" engines and had EPR for power settings.
 
Well, the EPR probes were full of deice fluid. Then, the copilot, who was making the takeoff, was complaining to the Captain that the thrust levers didn't "feel right" (not pushed far enough forward), but in ambiguous language. In response, the captain referenced the EPR gauges and insisted the thrust was correctly set. See my post in the Marine crash thread re: the conservative response to challenge. They ought to have aborted to find the cause of their disagreement.

Cross-cockpit experience gradient.... Yep, abort and work it out. One of our case studies from safety school.
 
The Airbus has Memory Items for Stall Indictions on takeoff and other phases of flight. It's simply a pitch and power combination.
Most of my operators aircraft have the Backup Speed System (BUSS):) that replaces Airspeed with AoA data and GPS derived Altitude
 

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