Virgin in ANU

[getjetsetgo]

Hey,
just got off work. before i left the BA engineers here in ANU working hard to get a Virgin 747 out. the aircraft had returned to stand becuz of an caution message about their main gear stearing. before i left the office they had just locked out the main gear steering and were preparing to push it to the end of the runway. has anyone ever seen this happen before. how often has it happend on a 747.

[Blink182]

If its in the MEL, then no problem............. Antigua departure involves a backtrack on the runway then a 180 turn at the end if I remember correctly. A tow or push seems a tad extreme just for a locked out MGS actuator.

[gas path]

A heavy 744 with locked out body gear steering puts a lot of strain on the body gear and the oleo seals, so a push to the end of the runway (if indeed that is what they are planning to do) does make some sense.:ok:

[spannersatcx]

32-53-1 Body Gear Steering System
Repair Interval - C NBR Installed - 1 NBR Reqd - 0 (M)(O)*
May be inoperative provided:
a) Body gear steering actuators are verified locked, and
b) Body gear steering is deactivated.
OPERATIONS (O)
1. With body gear steering deactivated or inoperative, turning capability will be reduced. See the following page for illustration depicting approximate minimum turning radii using differential thrust in addition to nose wheel steering.
As with all turns, the cockpit must travel outside the centreline of the turn to align the main path. The tip of the winglet describes the largest arc while turning and determines the minimum obstruction clearance path.
All other portions of the aircraft structure are within this arc. It should be noted from the TURNING RADIUS illustration that the wingtips are moved outboard about 11 FT, and travel 59 FT in front of the cockpit.
CAUTION: DO NOT ATTEMPT TO MAKE A TURN AWAY FROM AN OBSTACLE WITHIN 11 FT OF THE WING TIP OR WITHIN 59 FT OF THE COCKPIT.
2. Avoid sharp turns if possible, due to excessive tire scrubbing.
CAUTION: AVOID USE OF EXCESSIVE THRUST IN RAMP AREA DUE TO POSSIBLE DAMAGE OR INJURY FROM JET WAKE.

EICAS STATUS MESSAGES
BODY GR STRG SYS
MAINTENANCE (M)
1. Verify Body Gear Steering actuators are locked.
A. Perform the body gear steering actuator lock switch BITE test [MM 32-53-16 procedure 3.F.15(a) through (i)]. Bit status of “1” indicates actuators are locked. Bit status of “0” indicates actuators may be unlocked or indication system may be inoperative (refer to MEL Item 32-53-2).
B. If any bit status indicates “0”, verify actuator integrity as follows:
1) Depressurize hydraulic system #1.
2) Tow aircraft (using normal towing procedures) as follows, observing that no body gear steering
actuator extension or separation occurs:
a. Nosewheel left 45°, move 50 FT, stop.
b. Nosewheel right 45°, move 50 FT, stop.
3) Repressurize hydraulic system #1.
[C. If both PRI + ALT bit status indicates “0” on the same actuator then actuator integrity must be checked as above but in addition MEL 32-53-2 must be applied to inhibit a spurious take-off config warning.]
2. Deactivate Body Gear Steering using Procedure A and if necessary, Procedure B (actuator leak) and/or Procedure C (control module leak or pressure switch fault).

A. PROCEDURE A
1) Remove nose gear torsion link apex pin and secure upper torsion link so that it clears structure when turning.
2) Open and collar the P7 panel BODY GR STRG ARM AC and BODY GR STRG ARM DC circuit breakers.
3) Using tiller, steer left and right at least 25°. Verify that no body gear steering actuator extension occurs.
4) Reconnect nose gear torsion links.

[getjetsetgo]

i found out wat happened from an engineer that worked the flight. when the aircraft reached the end of the runway and started its 180 degree turn a status message came up about the main gear steering. after completing the turn the message went away. they tried veering to the right and the message came back up. they a/c returned to stand. a couple hours later they went for the tug and locked out the main gear and pushed it to the end of the runway. after all the vehicles cleared the runway the captain calls back in and says he returning to stand cuz he out of time.