Alignment occurs automatically whenever AC bus power is applied to AHRS. Alignment is complete when attitude and heading flags are removed from view. A new alignment is started whenever a power interrupt occurs.
Caution: During AHRS ground alignment, flight crew must assure airplane remains stationary until attitude and heading flags are out of view. If airplane is moved during final phase of ground alignment cycle, AHRS may align incorrectly with no apparent indication. Subsequent flight with an improper alignment may result in large errors in pitch, roll, and heading information..
The following steps will initiate a new AHRS ground alignment sequence into NORMAL mode without interrupting power to the cabin area.
GROUND SERVICE ELEC PWR (APU/EXT) Switch.......................ON AC BUS X-TIE Switch .................................................................... OPEN Right Bus Power Switch
(APU / EXT PWR / R GEN)...............................................................OFF
Left Bus Power Switch (APU / EXT PWR / R GEN).............................. CYCLE OFF THEN ON Right Bus Power Switch
(APU / EXT PWR R GEN)...................................................................ON
Note: Left and Right Bus switches must be turned on within 10 seconds of each other to prevent AHRS reversion to BASIC mode.
AC BUS X-TIE Switch ....................................................................AUTO
GROUND SERVICE ELEC PWR (APU / EXT) Switch...................OFF
* * * *
TOTAL AHRS FAILURE
If AHRS fails to automatically align after one minute:
AHRS-1 C/B OVHD B-05 AHRS-1 & 2 C/Bs EPC F-2 & 15 ...................................OPEN & RESET
Open C/Bs, wait 5 seconds, then reset C/Bs. Aircraft must remain strait and level at a constant airspeed until attitude and heading flag are out of view, approximately 55 seconds.
* * * *
Sec. 3 Page 104 MD-80
Rev. 05/15/95 #23 Continental Flight Manual
AIRSPEED UNRELIABLE / LOSS OF RADOME
Use this procedure anytime the airspeed system becomes inoperative or erroneous airspeed is suspected, with or without loss of radome.
Unreliable airspeed indications may result from blocking or freezing of the pitot system, or loss of part or all of the radome.
As soon as airspeed is determined to be unreliable, no difficulties in aircraft control should be encountered as long as pitch attitude and power settings are used as the primary reference and indicated airspeed readings are disregarded.
Note: If it can be determined that no significant wing leading edge
damage (resulting in increased stall speeds) has occurred and the
Speed Command system is operable, the Flight Crew may elect to
use Speed Command during terminal area flight and final approach.
Information for pitch attitude flying is contained in the following tables which are based on standard day temperatures for the given altitude. Linear interpolation for the target pitch attitude corresponding to the appropriate gross weight is permissible. The terminal area and final approach speeds contain an arbitrary margin to account for hail damage to the wing leading edges. The increased final approach speeds should be taken into account when determining landing field requirement.
Effects of Nose Radome Loss or Damage
Disrupts airflow over pitot tubes which may cause erroneous indicated airspeed/mach, overspeed warning, and improper function of systems that use air data inputs. Examples are autothrottle speed mode and autopilot IAS/Mach hold functions. The noise level will increase and low frequency buffeting may occur, but there is only a relatively small loss in aircraft performance. The buffeting is distinguishable from stall buffet in that it does not change greatly with changes in speed or attitude. No significant change will occur in aircraft handling characteristics, stall, or buffet onset speeds due to radome damage.
Effects of Hail Damage And Lightning Strike
Engine inlet damage may cause erroneous EPR indications. Wing leading edge damage may cause an increase in airplane stall speeds and degraded handling characteristics at or near stall (certain types of damage can cause airplane stall prior to stall warning). Angle of attack sensor damage will invalidate stall warning or Speed Command functions.
MD-80 Sec. 3 Page 105
Flight Manual Continental Rev. 05/15/95 #23
-217 MAX CLIMB SPEED 1.5 VS + 10 FLAPS / SLATS 0 / RET FLY TO PITCH ATTITUDE
ALTITUDE (FT) WEIGHT (1000 LB.) TARGET PITCH ATTITUDE (DEG) APPROX N1 RPM REQUIRED (%) APPROX AIRSPEED (KIAS) APPROX RATE OF CLIMB (FPM) STD TAT (°C)
0 80 120 160 20.1 12.8 9.3 85.3 85.5 85.4 194 235 270 5662 3811 2681 19.9 22.2 24.5
5,000 80 120 160 17.7 11.4 8.4 86.3 86.4 86.4 194 235 270 5230 3476 2420 10.8 13.5 16.2
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