727 tail skid?

[barit1]

I recall an early magazine article about the brand-new 727-100 about the time of first deliveries (EAL?). One photo was of the aft fuselage, including the (pre-D.B. Cooper) airstair and an extended tailskid.

The text described the skid as having a crushable cushion of aluminum honeycomb. I'm fairly sure the skid was retractable.

Is my memory correct? Did this feature remain on 727 production ships? Have other types copied this idea?

[DaveReidUK]

This thread

http://www.pprune.org/rumours-news/5...trike-fnc.html

includes a discussion of the 737NG's tailskid, which features a crushable cartridge.

[glendalegoon]

as someone who passed the flight engineer written exam on the Boeing 727, :-) I can tell you the skid was retractable. The exact design is beyond my memory.


there are other planes with tail skids or bumpers. another plane I flew had a tail skid bumper that did not retract but did exhibit a visual ''tell tale' that someone had hit it.


good luck

[con-pilot]

I recall an early magazine article about the brand-new 727-100 about the time of first deliveries (EAL?). One photo was of the aft fuselage, including the (pre-D.B. Cooper) airstair and an extended tailskid.

The text described the skid as having a crushable cushion of aluminum honeycomb. I'm fairly sure the skid was retractable.

Is my memory correct? Did this feature remain on 727 production ships? Have other types copied this idea?

Yes, all 727s had the tail skid and it was retractable, came up or down with the gear.

If the tail skid did not retract, there was a light on the FE's side panel, you had hell of a fuel burn penalty. I forget now how much, but it was shockingly high.

The 200s had a lot more tail strikes than the 100s did. I'd say that 99% of tail strikes were on takeoff, but I know of a guy that had a tail strike on landing in a 100. I was told it was a hell of a landing.

[Spooky 2]

I dare say that if you did a walk around on almost any 727-200 that had been in service for more than six months if not less you see that they had previously encounterd a tail strike. By this I mean the surface of the skid had been scuffed. Maint would simply replace the crushable cylinder and sign it off as okay to go. Tail scuffs were most common during takeoff. A strike during a landing would be highly unlikely unless someone really screwed up and probably call for some additional investigation off just how this happened.

If the skid did not retract the fuel penalty was significant as ealier noted. In addition part of the non normal checklist required the S/O to go back to the aft lavs and shut off the water so that when it expelled from the sink draink it would no impinge on the tail skid and form an ice glob thus adding to the drag issue and I suppose falling off during descent into warmer air.

You could just barely feel the skid touch the runway but the flight attendents sitting on the drop down jump seats in the very aft of the airplane new right away that something had happend. Usually only took them ten seconds to call the flight deck with the statement, "what just happened? These encounters were most common with a very heavy takeoff combined with a stong crosswind.

This is all significantly different than todays tail strikes in the 767/777/787/747 aircraft where they do not want you to pressurize the aircraft after a tail strike.

[barit1]

Thanks to all - for the reassurance my memory is not totally gone. Actually I was pretty confident it existed, but wasn't sure it carried on to the production 727, or whether it was only flight test hardware.

[misd-agin]

727-100
727-200


737 NG's(800/900)


767-300


777-300 (not installed on latest 777-300's with FBW software modification)

[B-HKD]

all -300ER have the FBW tailstrike protection and semi-levered MLG

correction: Thanks Wizofoz

As of line number 1162 the -300ER is no longer fitted with a tailskid.

[galaxy flyer]

This was quite impressive at night.

Indeed it was! Makes me wonder about what the B727 night time strike looked like.

[MarkerInbound]

I thought the penalty was 25% in climb and 10% in cruise. I talked with a pilot with some test pilot background and he said Boeing may have just made the numbers up without flight testing. He said Boeing could pick numbers that so horrible that the FAA would agree they would cover the situation without doing the flight test. Never had the tailskid stay down so I don't know what the real world numbers are.

[Wizofoz]

all -300ER have the FBW tailstrike protection and semi-levered MLG

Yes, but the software is being modified and all new-build 777s will not have the skid- I think we've already taken delivery of the first 300ER without one.

[No Fly Zone]

Interesting and thank you. I know nothing of the retractable 'skid plate' mechanics, but if it helped to prevent major damage on TO or landing, heck yes. Retractable with the LG is also new, but why the heck not; good engineering. What I do not quote get is why this protective device did not also include some kind of 2" - 3" 'feeler,' before the protective unit contacted the ground. My only guess is that when at V2 and attempting to rotate/lift off, the time is too short to make a substantial correction in AOA - or, none of the three-person crew needs any additional distractions at that instant. Perhaps the same thing. In other words, if the butt end is withing 3" of a strike, it is too late for any correction, they are going flying - no matter what surface may contact the ground; there is no time for AOA correction.
Of course, the next question has to be, in a 'normal' take off, how much butt end clearance is expected with the 727-200? I've seen hundreds, but only a few obvious strikes. Many looked close, but... Does anyone know what the performance engineers considered as 'normal?' Thanks. (no funny face here!)
As as as aside, I'll also note that my own observations of early jets, 727-100 and -200 especially were the first realization that 'jets,' generally took off with a *much* higher AOA than did the old props. To a young teen in the early 60s, the straight-wing props sort of begged to fly, while the jets could not get off the ground soon enough. To my then uninformed eye, the differences in raw power, initial AOA and initial climb were shocking; not only could the jet lift off early, it could maintain that high angle, but also accelerate. My guess is that more than a few pilots also had some difficulty understanding that new level of 'thrust. Ideas?

[aterpster]

barit1:

Thanks to all - for the reassurance my memory is not totally gone. Actually I was pretty confident it existed, but wasn't sure it carried on to the production 727, or whether it was only flight test hardware.

I have a lot of time in that beast, both the -100 and -200.

I only got a tail skid once. It was in a -200 making a Flaps 5 takeoff on Runway 8 at KABQ. We could feel it from the cockpit.

At the next station they inspected it and replaced the crush cartridge. The cartridge was not completely contracted so that was the end of it. But, had the cartridge been unable to absorb all the energy then it would have been reported to my chief pilot. Don't know where they would have led.

[Spooky 2]

No fears Apster as the Chief Pilot probably has done it once or twice himself!

[aveng]

The 727-100 had an electric motor driven tail skid, the -200 has a hydraulic tail skid.