Md-11 Lsas
03-27-2009, 07:32 AM
#21
...Whatever It Is!
Joined APC: Jul 2006
Posts: 4,680
03-27-2009, 05:48 PM
#22
Gets Weekends Off
Joined APC: Feb 2006
Position: DD->DH->RU/XE soon to be EV
Posts: 3,732
Talked to a bud last night and he has an interesting twist on this. If you watch the video on the "initial" nose-gear touchdown, take notice how utterly violent that nose touches down. In fact, in reports from witnesses at the airport it blew "both" nose gear tires from the aircraft.
With the length/arm of the MD-11 fuselage, the sheer size of the aircraft, and just watching how high it bounced it must have been just that, violent.
03-27-2009, 06:07 PM
#23
Gets Weekends Off
Joined APC: Jan 2006
Position: MD-11 F/O
Posts: 244
1.18.9 MD-11 Flight Control Computer Software Changes
In December 1995, the MD-11 FCC-907 software certification introduced a pitch
rate damper (PRD) control law to the previously certified LSAS. The -907 PRD utilized
inertial reference unit (IRU) pitch rate feedback in the LSAS elevator control laws to
counter pitch rate tendencies, thereby increasing the apparent static stability of the aircraft.
According to Boeing, this change was implemented as a product improvement to help
minimize MD-11 high-altitude upsets.94 Because it was decided during FCC-907
development not to affect the MD-11’s low-altitude, low-speed handling qualities, the
PRD was designed to phase-in and phase-out on a pressure altitude schedule (15,000 to
20,000 feet).
Boeing has developed an MD-11 FCC software upgrade—FCC-908—that was
FAA-certified on May 23, 2000. The upgrade primarily comprises modifications to three
subfunctions—PRD, pitch attitude protection (PAP), and positive nose lowering (PNL)—
of the LSAS. Boeing refers to these LSAS subfunctions as a low altitude stability
enhancement (LASE) package.
Boeing indicates that the LASE package implementation has two design goals.
The first is to employ the existing LSAS to provide deterrence against tailstrikes; Boeing
indicates this goal was established in response to the Safety Board’s Safety
Recommendation A-93-59. The second goal is to augment the natural aircraft longitudinal
handling qualities, via LSAS, in a manner approximating the handling qualities of the
existing DC-10. Both objectives are intended to facilitate a common type rating between
the MD-11 and the MD-10.95
The MD-11 FCC-908 software upgrade will activate the PRD control loop below
15,000-feet pressure altitudes at a reduced gain. Whereas the -907 PRD feature was
inactive at low altitudes, the -908 PRD will remain active at 30 percent strength from
approximately 17,500 feet down to takeoff/landing field elevation. Because the PRD
increases the apparent static stability, longitudinal handling qualities of the MD-11 will be
more like those of the DC-10.
The PAP subfunction is armed whenever an aircraft’s radio altimeter registers below
100 feet agl. The PAP uses radio altitude in conjunction with IRU pitch angle and pitch
attitude rate to provide nose-down elevator commands as a pilot begins to approach or
exceed the prescribed PAP pitch limit (30° pitch at 41 feet agl and 9.5° pitch at 0 feet agl).
This enhancement will slightly increase the control column force required to pitch the
aircraft beyond the prescribed limits, but the pilot otherwise retains full pitch-control
authority. As with all LSAS functions, the elevator command authority is mechanically
limited to 5° of deflection within the elevator electro-hydraulic actuator.
Boeing indicates that the PNL subfunction is intended to address both design goals
for the LASE package. The PNL subfunction provides a two-stage, nose-down elevator
command as the main wheels spinup for landing, which counters the nose-up tendency
typically experienced when landing ground spoilers are deployed. The PNL subfunction is
armed when aircraft radio altitude registers below 100 feet agl. The FCC signals, which
are used to command the auto ground spoilers to deploy, will cause the PNL subfunction
to command the first stage of the nose-down elevator of 3°. When the ground spoilers are
detected to be in excess of 10° of displacement, the second stage of the PNL increases the
nose-down command to 4°. Because the closed-loop PRD acts in conjunction with the
PNL, the nose derotation characteristics are essentially independent of the aircraft c.g. The
PNL commands are removed from the LSAS outputs at the same time that the flight mode
annunciator returns to the TAKEOFF mode (that is, after the nose wheel has been on the
ground for at least 20 seconds).
94 The Safety Board investigated some of these upsets, including the April 6, 1993, China Eastern
MD-11 accident at Shemya, Alaska, and the December 7, 1992, China Air accident at Anchorage, Alaska.
95 According to information provided by Boeing, the MD-10 is a modification of the DC-10 model that
was customized for FedEx. Like the MD-11, the MD-10 design incorporates a two-person flight crew
complement with associated changes to flight deck displays and system controls. The basic fuselage, wing,
control surface, flight control, and engine designs were not changed from those of the DC-10. On May 9,
2000, the FAA granted Boeing an amended type certificate for the MD-10 freighter. The FAA also approved
a common pilot type rating and landing proficiency credit for the MD-10 and -11, provided that the MD-11
incorporates FCC-908 to render its handling similar to that of the DC-10/MD-10.
Factual Information 50 Aircraft Accident Report
The PAP subfunction is being added to LSAS to mimic the tailstrike protection
that the MD-11 autopilot already provides for coupled landing and go-around operations.
03-27-2009, 06:21 PM
#24
Gets Weekends Off
Joined APC: Feb 2007
Position: headbanging
Posts: 954
I'm sorry it doesn't address your question about windshear, but this information isn't in my manual, and I think its interesting. Rather than start another thread, I thought I would just post it here.
1.18.9 MD-11 Flight Control Computer Software Changes
In December 1995, the MD-11 FCC-907 software certification introduced a pitch
rate damper (PRD) control law to the previously certified LSAS. The -907 PRD utilized
inertial reference unit (IRU) pitch rate feedback in the LSAS elevator control laws to
counter pitch rate tendencies, thereby increasing the apparent static stability of the aircraft.
According to Boeing, this change was implemented as a product improvement to help
minimize MD-11 high-altitude upsets.94 Because it was decided during FCC-907
development not to affect the MD-11’s low-altitude, low-speed handling qualities, the
PRD was designed to phase-in and phase-out on a pressure altitude schedule (15,000 to
20,000 feet).
Boeing has developed an MD-11 FCC software upgrade—FCC-908—that was
FAA-certified on May 23, 2000. The upgrade primarily comprises modifications to three
subfunctions—PRD, pitch attitude protection (PAP), and positive nose lowering (PNL)—
of the LSAS. Boeing refers to these LSAS subfunctions as a low altitude stability
enhancement (LASE) package.
Boeing indicates that the LASE package implementation has two design goals.
The first is to employ the existing LSAS to provide deterrence against tailstrikes; Boeing
indicates this goal was established in response to the Safety Board’s Safety
Recommendation A-93-59. The second goal is to augment the natural aircraft longitudinal
handling qualities, via LSAS, in a manner approximating the handling qualities of the
existing DC-10. Both objectives are intended to facilitate a common type rating between
the MD-11 and the MD-10.95
The MD-11 FCC-908 software upgrade will activate the PRD control loop below
15,000-feet pressure altitudes at a reduced gain. Whereas the -907 PRD feature was
inactive at low altitudes, the -908 PRD will remain active at 30 percent strength from
approximately 17,500 feet down to takeoff/landing field elevation. Because the PRD
increases the apparent static stability, longitudinal handling qualities of the MD-11 will be
more like those of the DC-10.
The PAP subfunction is armed whenever an aircraft’s radio altimeter registers below
100 feet agl. The PAP uses radio altitude in conjunction with IRU pitch angle and pitch
attitude rate to provide nose-down elevator commands as a pilot begins to approach or
exceed the prescribed PAP pitch limit (30° pitch at 41 feet agl and 9.5° pitch at 0 feet agl).
This enhancement will slightly increase the control column force required to pitch the
aircraft beyond the prescribed limits, but the pilot otherwise retains full pitch-control
authority. As with all LSAS functions, the elevator command authority is mechanically
limited to 5° of deflection within the elevator electro-hydraulic actuator.
Boeing indicates that the PNL subfunction is intended to address both design goals
for the LASE package. The PNL subfunction provides a two-stage, nose-down elevator
command as the main wheels spinup for landing, which counters the nose-up tendency
typically experienced when landing ground spoilers are deployed. The PNL subfunction is
armed when aircraft radio altitude registers below 100 feet agl. The FCC signals, which
are used to command the auto ground spoilers to deploy, will cause the PNL subfunction
to command the first stage of the nose-down elevator of 3°. When the ground spoilers are
detected to be in excess of 10° of displacement, the second stage of the PNL increases the
nose-down command to 4°. Because the closed-loop PRD acts in conjunction with the
PNL, the nose derotation characteristics are essentially independent of the aircraft c.g. The
PNL commands are removed from the LSAS outputs at the same time that the flight mode
annunciator returns to the TAKEOFF mode (that is, after the nose wheel has been on the
ground for at least 20 seconds).
94 The Safety Board investigated some of these upsets, including the April 6, 1993, China Eastern
MD-11 accident at Shemya, Alaska, and the December 7, 1992, China Air accident at Anchorage, Alaska.
95 According to information provided by Boeing, the MD-10 is a modification of the DC-10 model that
was customized for FedEx. Like the MD-11, the MD-10 design incorporates a two-person flight crew
complement with associated changes to flight deck displays and system controls. The basic fuselage, wing,
control surface, flight control, and engine designs were not changed from those of the DC-10. On May 9,
2000, the FAA granted Boeing an amended type certificate for the MD-10 freighter. The FAA also approved
a common pilot type rating and landing proficiency credit for the MD-10 and -11, provided that the MD-11
incorporates FCC-908 to render its handling similar to that of the DC-10/MD-10.
Factual Information 50 Aircraft Accident Report
The PAP subfunction is being added to LSAS to mimic the tailstrike protection
that the MD-11 autopilot already provides for coupled landing and go-around operations.
1.18.9 MD-11 Flight Control Computer Software Changes
In December 1995, the MD-11 FCC-907 software certification introduced a pitch
rate damper (PRD) control law to the previously certified LSAS. The -907 PRD utilized
inertial reference unit (IRU) pitch rate feedback in the LSAS elevator control laws to
counter pitch rate tendencies, thereby increasing the apparent static stability of the aircraft.
According to Boeing, this change was implemented as a product improvement to help
minimize MD-11 high-altitude upsets.94 Because it was decided during FCC-907
development not to affect the MD-11’s low-altitude, low-speed handling qualities, the
PRD was designed to phase-in and phase-out on a pressure altitude schedule (15,000 to
20,000 feet).
Boeing has developed an MD-11 FCC software upgrade—FCC-908—that was
FAA-certified on May 23, 2000. The upgrade primarily comprises modifications to three
subfunctions—PRD, pitch attitude protection (PAP), and positive nose lowering (PNL)—
of the LSAS. Boeing refers to these LSAS subfunctions as a low altitude stability
enhancement (LASE) package.
Boeing indicates that the LASE package implementation has two design goals.
The first is to employ the existing LSAS to provide deterrence against tailstrikes; Boeing
indicates this goal was established in response to the Safety Board’s Safety
Recommendation A-93-59. The second goal is to augment the natural aircraft longitudinal
handling qualities, via LSAS, in a manner approximating the handling qualities of the
existing DC-10. Both objectives are intended to facilitate a common type rating between
the MD-11 and the MD-10.95
The MD-11 FCC-908 software upgrade will activate the PRD control loop below
15,000-feet pressure altitudes at a reduced gain. Whereas the -907 PRD feature was
inactive at low altitudes, the -908 PRD will remain active at 30 percent strength from
approximately 17,500 feet down to takeoff/landing field elevation. Because the PRD
increases the apparent static stability, longitudinal handling qualities of the MD-11 will be
more like those of the DC-10.
The PAP subfunction is armed whenever an aircraft’s radio altimeter registers below
100 feet agl. The PAP uses radio altitude in conjunction with IRU pitch angle and pitch
attitude rate to provide nose-down elevator commands as a pilot begins to approach or
exceed the prescribed PAP pitch limit (30° pitch at 41 feet agl and 9.5° pitch at 0 feet agl).
This enhancement will slightly increase the control column force required to pitch the
aircraft beyond the prescribed limits, but the pilot otherwise retains full pitch-control
authority. As with all LSAS functions, the elevator command authority is mechanically
limited to 5° of deflection within the elevator electro-hydraulic actuator.
Boeing indicates that the PNL subfunction is intended to address both design goals
for the LASE package. The PNL subfunction provides a two-stage, nose-down elevator
command as the main wheels spinup for landing, which counters the nose-up tendency
typically experienced when landing ground spoilers are deployed. The PNL subfunction is
armed when aircraft radio altitude registers below 100 feet agl. The FCC signals, which
are used to command the auto ground spoilers to deploy, will cause the PNL subfunction
to command the first stage of the nose-down elevator of 3°. When the ground spoilers are
detected to be in excess of 10° of displacement, the second stage of the PNL increases the
nose-down command to 4°. Because the closed-loop PRD acts in conjunction with the
PNL, the nose derotation characteristics are essentially independent of the aircraft c.g. The
PNL commands are removed from the LSAS outputs at the same time that the flight mode
annunciator returns to the TAKEOFF mode (that is, after the nose wheel has been on the
ground for at least 20 seconds).
94 The Safety Board investigated some of these upsets, including the April 6, 1993, China Eastern
MD-11 accident at Shemya, Alaska, and the December 7, 1992, China Air accident at Anchorage, Alaska.
95 According to information provided by Boeing, the MD-10 is a modification of the DC-10 model that
was customized for FedEx. Like the MD-11, the MD-10 design incorporates a two-person flight crew
complement with associated changes to flight deck displays and system controls. The basic fuselage, wing,
control surface, flight control, and engine designs were not changed from those of the DC-10. On May 9,
2000, the FAA granted Boeing an amended type certificate for the MD-10 freighter. The FAA also approved
a common pilot type rating and landing proficiency credit for the MD-10 and -11, provided that the MD-11
incorporates FCC-908 to render its handling similar to that of the DC-10/MD-10.
Factual Information 50 Aircraft Accident Report
The PAP subfunction is being added to LSAS to mimic the tailstrike protection
that the MD-11 autopilot already provides for coupled landing and go-around operations.
03-27-2009, 07:15 PM
#25
Banned
Joined APC: Jan 2009
Posts: 133
Wow. So, they trick-f'd the -11 with software to make it behave like an MD-10, so they can get common type? I am sure Boeing pushed the snot out of this to the FAA because FedEx had promised to convert a ton of DC-10s...as long as it didn't cost them money (like having a separate MD-10 and MD-11 type rating/training program). It's starting to stink in here.
03-27-2009, 08:04 PM
#28
Gets Weekends Off
Joined APC: Feb 2007
Position: headbanging
Posts: 954
Then we'll deal with those issues. Regardless, I don't like how the whole 11/10 common type thing went down. Do you?
Last edited by HazCan; 03-27-2009 at 08:08 PM. Reason: not worth it.
03-27-2009, 08:13 PM
#29
Banned
Joined APC: Jan 2009
Posts: 133
Well, were you at FDX at the time this 'thing' went down? I have no issues with the whole 10/11 type. I do not believe it is any different than 75/76 or 74(multiple varients) etc
03-27-2009, 08:25 PM
#30
Gets Weekends Off
Joined APC: Feb 2007
Position: headbanging
Posts: 954
