Surge/stall: non ho ben capito la era differenza tra i due, comunque quel che so è N1 dropping e EGT puo aumentare piu del solito.
[QUOTE] E tra Severe damage e Stall/surge la condizione che le distingue è l'indicatore di VIB(vibration)..dico bene? [QUOTE]
Airbus in realtà non distingue tra Stall e Surge ... cito direttamente dalla "
Flight Operations Briefing Notes" di Airbus:
"An engine stall (also called engine surge) is in fact a compressor surge that can be caused by:
- An engine deterioration (e.g compressor blade rupture, or high wear)
- Ingestion or foreign objects (e.g bird strike) or ice
- A bleed sistem malfunction
- A malfunction of the engine control: fuel scheduling or fuel surge protection devices
In a jet engine, air compression is achieved aerodinamically, as the air passes through the stages of the compressor. If the air flowing over a compressor blòade stalls, the airflows disrupted, and the compressor can no longer compress the incoming air.
The high-pressure condition existing behind the stalled area may create a flow reversal towards the compressor air inlet, thus resulting in an immediate and large thrust loss.
During takeoff and high power settings, the engine stall is characterized by:
- One or more loud bangs
- Instant loss of thrust, resulting in a yaw moment
- Engine parameters (EPR/N1, N2 or N3) fluctuation and EGT increase
- Visible flames from the intlet and/or from the tailpipe
Flight crews who have experienced an engine stall at takeoff report that the bang is louder than any other noise they had previously heard in the cockpit.
It is often compared to a shotgun being fired a few meters away.
Because of the noise and yaw movement of an engine stall, flight crews sometimes incorrectly identify the occurrance as a tyre burst, or a bomb. In-service events show that a misunderstanding of an engine stall may result in rejecting take off above V1, causing a runway overrun.
At low power setting (e.g at thrust reduction at top of descent), the engine stall is charaterized by:
- one or more muffled bangs
- Engine vibrations
- Engine parameters fluctuations and EGT increased.
Anengine stall can result in an EGT overlimit condition because the airflow downstream of the combustion chamber is not sufficient to ensure the cooling of the turbine.
Engine stalls are harder to detect at low power.
The engine stall can be:
- Recoverable without crew action
- Recoverable with crew action (or FADEC action)
- Nor recoverable
Ti consiglio caldamente la lettura della
Flight Operations Briefing Notes -
Supplementary Techniques - Handling Engine Malfunctions della Airbus
che puoi trovare qui:
Safety Library | Airbus, a leading aircraft manufacturer
Troverai risposte a molte delle domande da te formulate.
Ciao
Paul