"THROTLLE HOLD" OR "THRUST HOLD" On B-767-300
Join Date: Jun 2001
Location: Surrounded by aluminum, and the great outdoors
Posts: 3,780
Likes: 0
Received 0 Likes
on
0 Posts
Are you sure about that?
Try it....it allows for manual adjustment of the thrust levers without deactivation of the autothrottle system
Try it....it allows for manual adjustment of the thrust levers without deactivation of the autothrottle system
Join Date: Nov 2000
Location: Grobelling through the murk to the sunshine above.
Age: 60
Posts: 562
Likes: 0
Received 0 Likes
on
0 Posts
It also allows the pilot to manually increase thrust on a working engine in the event of failure of the other. Not essential, of course, but often both desirable and permitted.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
McD and Airbus persisted in calling them "throttles" (holdover from piston jargon), while Boeing started the more generic "thrust lever" jargon. Why they didn't call 'em "speeder spring lever" is anybody's guess, but in the day of hydromechanical controls, that's exactly what they did. Ham Standard, Bendix, Woodward, and I'm sure many others used flyweight governors to control rotor speed and thus thrust.
Join Date: Jun 2001
Location: Surrounded by aluminum, and the great outdoors
Posts: 3,780
Likes: 0
Received 0 Likes
on
0 Posts
Everyone now calls them thrust levers, the "throttle Hold" comes from the auto-throttle system mode, hydromechanical-based engines do have a throttle of sorts, the manual fuel valve...if it's a by-product, then its a good one, try retarding the thrust levers before 80kts without disconnecting the autothrottle system and see what happens, the Throttle hold mode is there specifically on take-off, and other phases of flight to allow precisely that, or during a FLCH descent to allow the pilot to increase the thrust as desired to lessen the rate of descent, while at the same time the auto throttle system remains available to revert to speed mode when level-off is achieved...
Now....what your airline's callout when the FMA displays this mode may vary, the actual mode is "throttle hold" as this is precisely what has happened, the clutches have been de-energized to allow manual adjustment if desired, but the auto throttle system remains active to revert to the appropriate mode when needed, (climb after take-off, speed, when level off happens after a descent)
Now....what your airline's callout when the FMA displays this mode may vary, the actual mode is "throttle hold" as this is precisely what has happened, the clutches have been de-energized to allow manual adjustment if desired, but the auto throttle system remains active to revert to the appropriate mode when needed, (climb after take-off, speed, when level off happens after a descent)
Last edited by ironbutt57; 12th Apr 2012 at 05:57.
Join Date: Aug 2003
Location: Sale, Australia
Age: 80
Posts: 3,832
Likes: 0
Received 0 Likes
on
0 Posts
Throttle or thrust. Military (US) calls it a throttle in their jets. Even those built by Boeing. 
Should add that's fighters.
Should add that's fighters.
Last edited by Brian Abraham; 12th Apr 2012 at 06:51.
Join Date: Jun 2001
Location: Surrounded by aluminum, and the great outdoors
Posts: 3,780
Likes: 0
Received 0 Likes
on
0 Posts
Boeing calls them "thrust levers" that are commanded by an "autoTHROTTLE" system...or the pilot in case of the Autothrottle system being switched off...or active, but in the "throttle-hold" mode as annunciated on the FMA...
Join Date: Sep 2007
Location: Among camels and dunes
Posts: 425
Likes: 0
Received 0 Likes
on
0 Posts
A copy and paste from Boeing 777 FCOM in 2 parts:
In flight:
Push (after lift-off with takeoff reference thrust limit displayed) removes takeoff and climb derates and assumed temperature thrust reduction A/T in HOLD, activates A/T in THR REF mode disarms LNAV and VNA V, if armed between 50 feet and 400 feet, selects TO/GA roll mode above 400 feet, selects TO/GA roll and pitch modes
*Annunciations are: THR autothrottle applies thrust to maintain the climb/descent rate required by the pitch mode THR REF thrust set to the reference thrust limit displayed on EICAS IDLE displays while the autothrottle moves thrust levers to idle; IDLE mode is followed by HOLD mode HOLD thrust lever autothrottle servos are inhibited. The pilot can set thrust levers manually*
I hope this helps somewhat! Will find the link with respect to take-off!
In flight:
Push (after lift-off with takeoff reference thrust limit displayed) removes takeoff and climb derates and assumed temperature thrust reduction A/T in HOLD, activates A/T in THR REF mode disarms LNAV and VNA V, if armed between 50 feet and 400 feet, selects TO/GA roll mode above 400 feet, selects TO/GA roll and pitch modes
*Annunciations are: THR autothrottle applies thrust to maintain the climb/descent rate required by the pitch mode THR REF thrust set to the reference thrust limit displayed on EICAS IDLE displays while the autothrottle moves thrust levers to idle; IDLE mode is followed by HOLD mode HOLD thrust lever autothrottle servos are inhibited. The pilot can set thrust levers manually*
I hope this helps somewhat! Will find the link with respect to take-off!
Join Date: Sep 2007
Location: Among camels and dunes
Posts: 425
Likes: 0
Received 0 Likes
on
0 Posts
Found more, copy and paste of FCTM B777-300ER:
The PM should verify that takeoff thrust has been set and the throttle hold mode (HOLD) is engaged. Once HOLD annunciates, the autothrottle cannot change thrust lever position, but thrust levers can be positioned manually. The HOLD mode remains engaged until VNAV engagement or another thrust mode is selected.
Note: Takeoff into headwind of 20 knots or greater may result in HOLD before the autothrottle can make final thrust adjustments.
The HOLD mode protects against thrust lever movement if a system fault occurs. Lack of the HOLD annunciation means the protective feature may not be active. If HOLD annunciation does not appear, no crew action is required unless a subsequent system fault causes unwanted thrust lever movement. As with any autothrottle malfunction, the autothrottle should then be disconnected and desired thrust set manually.
The PM should verify that takeoff thrust has been set and the throttle hold mode (HOLD) is engaged. Once HOLD annunciates, the autothrottle cannot change thrust lever position, but thrust levers can be positioned manually. The HOLD mode remains engaged until VNAV engagement or another thrust mode is selected.
Note: Takeoff into headwind of 20 knots or greater may result in HOLD before the autothrottle can make final thrust adjustments.
The HOLD mode protects against thrust lever movement if a system fault occurs. Lack of the HOLD annunciation means the protective feature may not be active. If HOLD annunciation does not appear, no crew action is required unless a subsequent system fault causes unwanted thrust lever movement. As with any autothrottle malfunction, the autothrottle should then be disconnected and desired thrust set manually.
