Spacepope From Vatican City State (Holy See), joined Dec 1999, 1923 posts, RR: 1 Posted (6 years 11 months 1 week 6 days 18 hours ago) and read 932 times:
Cdfmxtech From United States, joined Jul 2000, 1332 posts, RR: 35 Reply 1, posted (6 years 11 months 1 week 6 days 18 hours ago) and read 904 times:
1) Under what circumstances is this called for, and is it common?
Never worked the -40, but assuming it is like the -30 (and I'm 99.9% sure it is), there is a Center Gear Isolation Switch on the Ldg Gear Ctrl panel. It allows the center gear to remain retracted.
I'm not sure what procedures are for this, but I know it can only be done at certain weights.
2) Once on the ground, is there any way to extend the center gear besides using jacks?
On the ground, the Center gear can be retracted simplay by pinning the other gears (Main and Nose, releasing the brakes and putting the gear handle UP. The aircraft doesn't have to be jacked.
Sllevin From United States, joined Jan 2002, 3376 posts, RR: 9 Reply 2, posted (6 years 11 months 1 week 6 days 18 hours ago) and read 903 times:
It's all related to weight. Others will likely have technical details, but I do know that JAL for several years operated their "domestic" 40's with the entire center gear assembly removed to reduce weight.
XFSUgimpLB41X From United States, joined Aug 2000, 3314 posts, RR: 37 Reply 3, posted (6 years 11 months 1 week 6 days 17 hours ago) and read 898 times:
It was probably some sort of a test to make sure the center gear extension override was working- cdfmxtech is correct in assuming that there is that switch in the -40 also. The only time NW pilots are trained to land without the extending center gear is in a two engine out landing- a very dire situation indeed. You land at Vga speed instead of ref+5 also in that situation. I need to hunt through the manuals to find the weights where this is permitted. It would be interesting to find out what they were doing in this situation.
XFSUgimpLB41X From United States, joined Aug 2000, 3314 posts, RR: 37 Reply 4, posted (6 years 11 months 1 week 6 days 17 hours ago) and read 895 times:
You can see the gear isolation switch right next to the gear lever. You can see the locking pin and chain hanging down from it. Unfortunately i dont see any weights that are placarded next to it- nor is the photo clear enough to read them if I could. Oh well...
Dc10hound From United States, joined Dec 2000, 463 posts, RR: 6 Reply 5, posted (6 years 11 months 1 week 6 days 7 hours ago) and read 835 times:
On the ground, the Center gear can be retracted simplay by pinning the other gears (Main and Nose, releasing the brakes and putting the gear handle UP. The aircraft doesn't have to be jacked.
It's not really quite that simple. You have to depressurize the centerline gear shock strut before you retract the gear on the ground. The MM has a big, fat WARNING note on this.
I suppose that overriding the gear handle to UP to retract the centerline gear would work, but the MM tells you use the manual centerline control valve handle, which is accessed through the right main landing gear wheelwell.
"Eagles soar. But weasels never get sucked into jet intakes.."
Cdfmxtech From United States, joined Jul 2000, 1332 posts, RR: 35 Reply 6, posted (6 years 11 months 1 week 6 days 4 hours ago) and read 821 times:
DC10...U are correct.
I forgot all about that handle (Please refresh my memory on it's location. I can kind of see it from middle to forward in the ww & it was thru an opening or panel).
I did remember the strut, but forgot all using the handle. And I was involved with the replacement of a ctr gear actuator when I first started...go figure.
Dc10hound From United States, joined Dec 2000, 463 posts, RR: 6 Reply 7, posted (6 years 11 months 1 week 6 days 4 hours ago) and read 819 times:
The centerline gear manual control valve is located in the forward area of the right main wheel well inboard bulkhead. There is a viewing cutout adjacent to the valve to view the gear while you raise or lower it.
There is also an access hole located just aft of the aft brake cooling duct and above the keelbox. It is used to release the forward door drive link.
Cdf:
I almost forgot about the strut too. (It's been a while since I've even smelled a DC-10...)
"Eagles soar. But weasels never get sucked into jet intakes.."
FDXmech From United States, joined Mar 2000, 3251 posts, RR: 48 Reply 8, posted (6 years 11 months 1 week 6 days 3 hours ago) and read 816 times:
On a few occasions I've seen the centerline gear MEL'd & deactivated in retract due to mechanical issue's. Of course the aircraft will take a substantial hit inasfar as weight restrictions go (basically converting a -30 to a -10).
TimT From United States, joined Jun 2001, 168 posts, RR: 0 Reply 10, posted (6 years 11 months 1 week 4 days 22 hours ago) and read 720 times:
Just for additonal info- the picture in the first posting is a -30. The -40 #2 engine cowl looks like a "coke bottle". And don't forget, the DC-10-10 did NOT have a center MLG.
747Teach From United States, joined Nov 2000, 176 posts, RR: 2 Reply 12, posted (6 years 11 months 1 week 4 days 8 hours ago) and read 671 times:
TimT: The aircraft in Spacepope's posting, aircraft 1155, carries registration N155US. It is a DC10-40 series, factory serial number 46764, block unit number 46A015. It has been retired. Regards,
Spacepope From Vatican City State (Holy See), joined Dec 1999, 1923 posts, RR: 1 Reply 13, posted (6 years 11 months 1 week 4 days 6 hours ago) and read 658 times:
Thank you all for your very informative responses!
Question 2 still remains unanswered. You addressed the process of retracting it on the ground in excellent detail, but can that process be reversed to extend the main gear once on the ground.
Another question now: What is the savings involved in eliminating one cycle off of that CMG? Is it just tire wear, or is the maintainence really that expensive?
FDXmech From United States, joined Mar 2000, 3251 posts, RR: 48 Reply 14, posted (6 years 11 months 1 week 4 days 5 hours ago) and read 650 times:
Extending the centerline landing gear on the ground is done utilizing the same centerline gear manual control valve as Dc10hound stated in how to retract the CLG.
I've never seen the CLG remain stowed except for maintenance problems which required the CLG to be stowed until the problem is fixed.
The company does not like operating the -30 in such a manner as it is limited in its scope of operations.
Tulsarefueler From United States, joined Aug 2002, 41 posts, RR: 0 Reply 15, posted (6 years 11 months 1 week 3 days 11 hours ago) and read 598 times:
if the numbers i have are correct here they are:
(all numbers are based on center gear retracted)
max taxi is 443,000 lbs some 433,000 lbs
mtow is 440,000 lbs
inflight with landing flaps is 424,000 lbs some 406,000 lbs
mlw is 363,500 lbs
max zero fuel is 350,000 lbs
these are several dc-10's i have worked around. hope
that this helps.
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