JAM747 From United States of America, joined Feb 2005, 550 posts, RR: 1 Posted (8 years 5 months 1 week 3 days 15 hours ago) and read 30912 times:
When a jet aircraft flies through rain does the ingestion of water with air affect the engine's performance such as fuel burn, thrust, wear etc? Can rain be too heavy that it causes a engine stall? How is it determimed if the rain fall is too dangerous to fly in? Do pilots take different precautions for engine settings during rain?
Water injestion is indeed tested during certification...as I recall, at least one engine manufacturer aims a fire hose at the engine to make sure it keeps going The testing varies by manufacturer, however they all test for it.
Quoting JAM747 (Thread starter): Do pilots take different precautions for engine settings during rain?
Well, I'm no jet driver, but maybe one of you guys could chime in here...I do believe that many makes of engine require the ignitors to be turned on when entering dark clouds/heavy precipitation...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
Jamie757 From , joined Dec 1969, posts, RR:
Reply 2, posted (8 years 5 months 1 week 2 days 19 hours ago) and read 30722 times:
Quoting KELPkid (Reply 1): Water injestion is indeed tested during certification...as I recall, at least one engine manufacturer aims a fire hose at the engine to make sure it keeps going The testing varies by manufacturer, however they all test for it.
Testing of the GE90-115B a few years back....
As I understand from previous posts on the matter, the engine must demonstrate no loss of rated thrust during the water ingestion test.
Here is a rather miraculous instance where a 737 lost both engines but landed safely on a levee.
During descent from FL350 for an IFR arrival to New Orleans, the flight crew noted green and yellow returns on the weather radar with some isolated red cells, left and right of the intended flight path. Before entering clouds at FL300, the captain selected continuous engine ignition and activated engine anti-ice systems. The crew selected a route between the 2 cells, displayed as red on the weather radar. Heavy rain, hail and turbulence were encountered. At about FL165, both engines flamed out. The APU was started and aircraft electrical power was restored while descending through abou FL106. Attempts to wind-mill restart the engines were unsuccessful. Both engines lit-off by using starters, but neither would accelerate to idle; advancing the thrust levers increased the EGT beyond limits. The engines were shut down to avoid a catastrophic failure. An emergency landing was made on a 6060 feetx120 feet grass strip next to a levee without further damage to the aircraft.
Investigation revealed that the aircraft encountered a level 4 thunderstorm but engines flamed out, though they had met the FAA specs for water ingestion. The aircraft had minor hail damage; the #2 engine was damaged from overtemperature.
PROBABLE CAUSE: "A double engine flameout due to water ingestion which occurred as a result of an inflight encounter with an area of very heavy rain and hail. A contributing cause of the incident was the inadequate design of the engines and the FAA water ingestion certification standards which did not reflect the waterfall rates that can be expected in moderate or higher intensity thunderstorms."
Follow-up / safety actions:
After the incident, OMB 88-5 and AD 6-14-88 were issued to require minimum rpm of 45% and to restrict the use of autothrust in moderate/heavy precipitation; engine modification was provided for increased capacity of water ingestion.
Despite of this AD, a Continental Airlines B737-300 suffered a nr.1 engine flameout while descending through heavy precipitation with throttles at flight idle, July 26, 1988. The co-pilot warned the captain of the fact that idle descent was contrary to recently published procedures, but idle descent was continued.
F14D4ever From United States of America, joined May 2005, 319 posts, RR: 4
Reply 7, posted (8 years 5 months 1 week 1 day 9 hours ago) and read 30385 times:
Quoting Airfoilsguy (Reply 3): Here is a rather miraculous instance where a 737 lost both engines but landed safely on a levee.
Another more recent instance involved Garuda PK-GWA 733 flying AMI-JOG. It flew into the confluence of two huge storms, and experienced a dual flameout, despite the pilots having set ignitors to 'continuous'. This precipitated the redesign of the CFM56 front end, including moving the splitter rearward so the booster swallows less water, and changing the spinner to the current 'coniptical' shape, a hybrid conic / elliptical shape which more effectively flings hail and water further out radially past the aforementioned splitter.
HAWK21M From India, joined Jan 2001, 31792 posts, RR: 55
Reply 9, posted (8 years 5 months 1 week 1 day 3 hours ago) and read 30305 times:
Quoting KELPkid (Reply 1): Well, I'm no jet driver, but maybe one of you guys could chime in here...I do believe that many makes of engine require the ignitors to be turned on when entering dark clouds/heavy precipitation...
Isn't the Def of Turbulence subject to the Interpretion of the Pilot flying.Some would consider shaking in their seat due Turbulent weather to be Turbulence.
From what I recall, after loosing a little bit of altitude they were able to restart both engines. I am hoping someone who knows more about it can shed some light, or at least find a link to the thread on the incident. From what I recall, the flight was going to Europe.
F-WWAI From Andorra, joined Dec 1999, 131 posts, RR: 0
Reply 13, posted (8 years 5 months 4 days 21 hours ago) and read 29741 times:
I was really tempted to answer that the engine would become wet... but I think you were after something else.
Lets resume in terms of
* effective water capture
The quantity of water entering the engine is a function of aircraft speed, (core) inlet size, droplet size and nuber of droplets per air volume in front of the engine.
high aircraft speed plus many big raindrops = high quantity of water.
* water/air ratio in the combustion chamber
You may imagine that, if the water/air ratio increases above a certain limit, then the energy developped by the combustion will entirely be used up for water vapourisation and heating, and the combustion will nomore be sustained. The flame extiguishes because there are nomore sufficient radicals in recirculation to light the injected fuel.
Since the water capture is fixed by the parameters above, the water /air rate is then governed by the (core) engine airflow. It is highest at IDLE and lowest at MAX power.
We would therefore not expect the engine to stall in any case of rainfall, but the risk of flameout is increased at idle. Engine control is normally tailored to take this into account and guarantee a minimum airflow, sufficient to avoid excessive water/air ratio. Modern engines have, in top of these protections, also an automatic relight feature to recover from a flameout.
Pilotaydin From Turkey, joined Sep 2004, 2539 posts, RR: 50
Reply 14, posted (8 years 5 months 4 days 4 hours ago) and read 29604 times:
turbulence CAN cause compressor stall, due to erratic air flow patterns at engine inlet, rainfall doesnt cause this, rain and wet weather can cause flameout...so always put those start switches into FLT mode baby!
The only time there is too much fuel onboard, is when you're on fire!