Landing gear retraction requirements

[transducer]

Hi Guys

Anybody know if there are any FAR/JAR certification requirements for the maximum time that it must take for the landing gear to retract?

Thanks

[Dream Land]

20 seconds?

[tristar 500]

Retraction times

The 757 M.M. quotes retrraction times as 20seconds & extension times as 32 seconds. These are hangar times.

Tristar 500

[glhcarl]

The maximum landing gear retraction time for the L-1011 is 14 seconds.

[Mad (Flt) Scientist]

Originally Posted by transducer

Anybody know if there are any FAR/JAR certification requirements for the maximum time that it must take for the landing gear to retract?

Since there are no requirements that the gear retract at all, I doubt there is an explicit time for a retracting gear to do so. (Though I'll go check out of curiousity) The various times people are quoting are for their aircraft, not a regulatory time.

25.1301 would probably snag anyone with a 'retractable' gear that took an hour to retract (failure to perform intended function) but the practical limit is that the FARs will require that your performance be based upon the specified performance of the gear for retraction. So if you want to have decent climb performance you need a gear with a decent speed.

[speedrestriction]

I seem to recall from the JAR ATPL Performance exam that there is a maximum time for MEP aircraft at least. I'll see what I can find. Related to SE go-around performance if I recall correctly.

sr

[411A]

The maximum landing gear retraction time for the L-1011 is 14 seconds.

Yes, indeed, 'tis true.
Usually accomplished in ten to eleven.
We time this on acceptance flights out of heavy maintenance...always.
Standard procedure.

[transducer]

Thanks for the info.

I was thinking more along the lines of part 121 aircraft. Had a deferrable snag the other day with a hydraulic pump. The MEL, as one of the operation requirements, refers to the "Flight with Landing Gear Down" supplement. The reason is that not enough volume of fluid is running through the system causing the gear to retract at a slower rate than normal. The MEL also cautions that a "gear disagree" warning might occur if the gear is not up and locked within 20 seconds due to the slow cycling. Consulting the performance penalties in the supplement, which are fortunately not rocket science to calculate, lead you to think that due to the gear not retracting within a required time you will not meet the obstacle clearance criteria within the segment climb if you "drop a donkey" at V1. Hence the question. Me thinks it is in the line of 20 seconds?!

[FE Hoppy]

I think it's a case of first segment not being over till the gear is up so if the time it takes is not known then you should use gear down perf. The time it takes to retract normally is used to define the end of first segment so this should be stated in the AFM for use in calculations.

[Pugilistic Animus]

I seem to recall some discussion about First Segment Limited TO's and some interesting solutions


PA