Reverse thrust after touchdown
04-16-2012 | 05:57 PM
#12
Chief Jeppesen Updater
Joined: Oct 2005
Posts: 3,080
Likes: 0
From: Executive Transport Driver
Smaller aircraft are probably more prone to issues. In the Citation Encore it was a BIG no no to deploy without all gear on the ground. Not for directional (yaw) control, but because the engines were above the CG. Deploying the TRs with the nose of the ground could result in the nose being "rotated" back into the air and either ending up off the ground (with TRs deployed) or a tail strike.
The CRJ, CL604 and GLEX are all able to deploy TR prior to touching down. In theory you could also spool the engines on each of those types with the nose off (although I don't know why you would want to.)
The CRJ, CL604 and GLEX are all able to deploy TR prior to touching down. In theory you could also spool the engines on each of those types with the nose off (although I don't know why you would want to.)
04-16-2012 | 06:38 PM
#13
Gets Weekends Off
Joined: Jul 2007
Posts: 4,772
Likes: 1
From: 744 CA
We unlock..and apply reversing thrust as soon as the mains touchdown (signaled on the classic by the spoilers deploying )....generally you will be at or near target reverse thrust before the nose gear is flown on to the runway....
Slow deployment of the TRs has a dramatic effect on landing distance and brake energy required to slow the whale...and directly relates to high brake temps.
Slow deployment of the TRs has a dramatic effect on landing distance and brake energy required to slow the whale...and directly relates to high brake temps.
04-17-2012 | 06:21 PM
#14
Line Holder
Joined: Nov 2008
Posts: 31
Likes: 0
Reverse thrust
During certification of the DC-9-80(Super 80), an aircraft was being flown by an FAA pilot and a Douglas test pilot. Upon main gear touchdown the FAA pilot selected max reverse thrust (something only the boldest of 9 pilots would have done). One engine went to max while the other lagged behind. Directional control was lost and the aircraft was scuttled. The investigation revealed that airflow across the rudder was impeded by high reverse thrust values reducing rudder authority. There was a restriction placed on DC9 type aircraft that only idle reverse was to be applied until the nose wheel was on the ground. Don't remember if this was a company or FAA mandate. Douglas merged with McDonnell and the aircraft were re-designated MD80.
04-18-2012 | 03:13 AM
#15
Prime Minister/Moderator
Joined: Jan 2006
Posts: 45,186
Likes: 807
From: Engines Turn or People Swim
Not for the CRJ. Somewhat complicated sensor logic prevents reverser deployment until some combination of wheel spin and WoW. It will let you at open them with the nose wheel off and I have actually deployed full reverse in that condition. My current company's SOP says to wait until the nose is down though, and I have no problem with that.
Remember...required runway length is always calculated without the TR's so you should never actually need them unless something else has gone significantly wrong. The conditions when you might be tempted to get early TR (contaminated RWY) are also conditions that could lead to loss of directional control.
Last edited by rickair7777; 04-18-2012 at 03:30 AM.
04-18-2012 | 04:54 AM
#16
Chief Jeppesen Updater
Joined: Oct 2005
Posts: 3,080
Likes: 0
From: Executive Transport Driver
Not for the CRJ. Somewhat complicated sensor logic prevents reverser deployment until some combination of wheel spin and WoW. It will let you at open them with the nose wheel off and I have actually deployed full reverse in that condition. My current company's SOP says to wait until the nose is down though, and I have no problem with that.
Remember...required runway length is always calculated without the TR's so you should never actually need them unless something else has gone significantly wrong. The conditions when you might be tempted to get early TR (contaminated RWY) are also conditions that could lead to loss of directional control.
Remember...required runway length is always calculated without the TR's so you should never actually need them unless something else has gone significantly wrong. The conditions when you might be tempted to get early TR (contaminated RWY) are also conditions that could lead to loss of directional control.
04-18-2012 | 05:21 AM
#17
Gets Weekends Off
Joined: Feb 2008
Posts: 651
Likes: 0
From: Retired
This is one of those cases, like so many, where you can not make one rule and go at the industry with a big paint brush. Some airplanes, as others have noted, have directional control concerns that call for waiting to pull the TRs until the nosewheel is down. Others, such as the 747, have no such problems and can (and on slippery surfaces should) have the TRs pulled as soon as the mains are down.
Do what is right for your airplane in your situation.
Do what is right for your airplane in your situation.
04-18-2012 | 05:53 AM
#18
Line Holder
Joined: Jan 2010
Posts: 275
Likes: 4
From: Supine
Remember...required runway length is always calculated without the TR's so you should never actually need them unless something else has gone significantly wrong. The conditions when you might be tempted to get early TR (contaminated RWY) are also conditions that could lead to loss of directional control.
Thread
Thread Starter
Forum
Replies
Last Post
