B727-200 Autopilot
 

Any old timers in here can shed the differences between the Sperry SP-50/and SP-100 or SP-150 of this old bird and its individual quirks ) like failure tp capture altitude and causes of AP trip offs, etc)?

How did it behave in severe weather, Icing,Lightning strikes?

How reliable was it with degraded hydraulic power and how it handled one eng out auto coupled approaches?

Thanks

Don't know the specific model numbers of autopilot you speak of but I flew various different models of the B727 from the -100 through the -200 series.


We had a very basic autopilot on our original aircraft, certainly had no altitude capture, that was done manually then Alt Hold was selected. That AP basically could just hold pitch and heading.


We acquired some more advanced -200's in a merger and these aircraft had IAS hold and Altitude capture as well as VS hold.


As far as how it performed in the scenarios you mention, I don't remember too many failures, the AP was pretty basic but it worked well.


You certainly wouldn't be using it on the later stages of an engine out approach though, it was no triple 7 !

Once had a 727-200 auto pilot that disengaged when altitude aquire reached due to a dud (shorted) bulb in the annunciator. From memory SP150 had the aux Nav option that used a IRU. Had up to 10 way points in memory.

727. Auto Pilot
 

Thank you avenge

SP-50 and SP-150 are the only two I have seen documented but have seen also SP-100

According to its AFM limitations it is certified fown to 80 ft in IMC and 50ft VMC and certified for use with one eng. out. It has to be OFF for two engine out. This beasy can do a single eng go Around no hassles provided speed is good around 200kts and in trim.

Yes a rather ancient AP. I saw some on tge mide selector knob you press for Mach Hold. I guess that was the same function for speed hold.That was ln the SP-150 block. This more modern version had a vertical speed wheel similar to those on 747 Classics. It also had Alt Sel and HDG slect buttons rather than toggle switches.

Those rquipped with Autothrottles: was speed controlled by Speed bugs. EPR was controlled by the EPR "set" knob gauge bug drivers I suppose.By setting the bugs and selecting the AT switch to ON it automatically rolled the throttles to the target EPR on takeoff or only after manual setting if the throttles by tge PF and FE?

Just a few years ago I was maintaining many of them down to CAT IIIa in A/B mode. How quickly information is forgotten I believe all SP-150. I remember it's Achilles heel being the elevator position transmitters causing everything from porpoising to A/P disconnect after LOC CAP (performs a self test and verifies asymmetry).

Thank you grounded27.Useful to know.Were the AP tripoffa with Loc capture very common or one off?

727 AP anomalies
 

Thanks OK465

Great stuff..why dont they teach us good stuff like that in the AFM!!

Correct Elev Low Pressure light.I think located on the centre fwd panel lefy of tge rydder and elev position indicator and below the Capt Marker beacons.Stab trim cut off on red.

Was the SP-150 AP on 727-200 certified to Cat2A or just Cat1?

Was there also an SP-100 fitted on Miss Piggy?

autoland
 

One of the last 727 off the production line had auto land and auto brakes, as well as a performance data computer and driven EPR bugs

Wow.That's NEWS! I knew I saw the autobrake control knob in one of the 727 OVHD panel but eas totally unaware if the Autoland capability( whicj I was hoping it would incorporate considering its design was inspired byvthe HS Trident).Am sure it had Autothrottles too this Autoland certified variant.

Was that the same PDC that found its way into the 732-Advc ?

Probably the most common failure was the autopilot tripping off in A/B mode (just about all our aircraft were CAT3A autoland capable) A/B dual land a short while after LOC CAP. I do not believe it would happen in A or B for the above mentioned problem. The operator I speak of had over a hundred of them.

grounded 27 do you know if yhose Cat3A approved planes were post 1984?

Cheers

Unfortunately I do not have access to any of their records any more.

I'm impressed, all the autopilots knew how to do on our 727s was to break.

But we only had two -100s and an early -200, so nothing advanced. I cannot remember ever letting an autopilot do an approach in the 727s, except in the sim during recurrency.

It's been awhile and I was a "wrench", but Eastern's later -200s all had autobrakes and autoland, but I don't think any of them had autothrottles. We used the autoland all the time in ATL and SEA.

GF

Our -200 had auto-brakes and spoilers, but that was it as far as automation went. To be honest I cannot remember if we had altitude capture on the autopilot or not. I really don't think so. No auto-throttles of course.

I had a love/hate relationship with the auto-spoilers on the -200. Sometimes it would save a good landing and other times destroy a great landing. I never got the number of grease on landings I had in the -100s in the -200s, but in my defense I didn't have near as much time in the -200 that I did in the -100.

No auto throttles. No auto spoilers. No auto brakes. No altitude capture. Capture altitude with the pitch/roll knob and engage ALT HOLD switch.

PDCS? Computer drove EPR bugs. Gave altitude/thrust data. Kinda dumb. If you flew a heavy flight after a light flight the EPR bugs would read too low for a while in cruise until it eventually figured out "hey, I need more power." If you flew a light flight after a heavy flight the EPR bugs would read to high ( thinking the plane was still to heavy). So you could either scream around the sky at high Mach or set a lower EPR and wait for the PDCS(?) to finally catch up in cruise. It would the awhile. Ten to 20 minutes???

K-factor (drag index) could be checked on the status page. 1.00 normal, light a/c could read as low as .95 on arrival, heavy a/c could have K-factors(drag index) as high as 1.05(+/-). Double check on preflight would give you a clue if you could trust PDCS(???) EPR settings for cruise. Low K factor and heavy flight = set higher EPR's for initial cruise power. High K factor and light flight = set lower than commanded EPR settings.

Memory says K-factor was on page 4/4(?) of status (data?) page. Bleed valves were zeroes and ones on another data/status page. They'd change as you cycled the engine bleeds.

Alaska 727's had auto throttles and auto brakes(?). Not sure if they had auto land. We weren't certified so when we flew their a/c we weren't supposed to use any of their fancy automation. ;-)

-19(?) engines. Rocket ship. Huge improvement over the -15's(?).

Yep, that was me, the faster the better, especially heading for a RON or on Friday night heading home.

We really didn't care about fuel burn/cost. Taxpayers paid for the fuel. :E

Well actually they paid for everything.

The 727 went out of production in 1984 - the last delivery to FedEx in September 1984.
Obviously, operators were free to incorporate aftermarket 'update' via STC - UPS even did a re-engine with Rolls Tay engines - but no changes to the production configuration post 1984 since there was no production :E

Autoland on a 727 ?


Find that rather hard to believe, can anyone support that ?

I'm almost certain that Eastern Airlines had Block V autoland on a few of their 72's.

It is a scary thought.

I've got an Eastern Airlines Flight Manual that lists the requires for CAT IIIa approaches. The first hint is having "A" "B" or "AB" options on the autopilot pitch channel selector.

Dash 15s had 15,500 pounds of thrust. There were -17 and -17R engines with 900 pounds more thrust than the -15. The -17Rs kicked it up another 1000 pounds during an engine failure with the APR armed.

Then there are the Valsan conversions with -217 or -219 engines. The -219s are running 21,700 pounds of thrust down the runway. Ridden in one of those a couple times, true rocket ship performance.

Used to fly a converted -231 into a freighter. Had -219s on the sides and a -17 in the center. Ferrying with 2,000lbs ballast for CG purposes with 20,000lbs of gas the only direction on is going is skyward with IVSI pegged. Controllers used to ask "You guys really a 727?":ok:

Now for the old autopilot with dual channel. I used to engage the aileron portion and hand fly the pitch rather than using the speed/Mach mode on the pitch as too much porpoising resulted. Probably because of CG shifts do to Pax and galley cart movements. On the old -7 powered lead sleds at heavier weights and warm OATs, one may have to descend to regain climb speed.

I already did, yes I know it is hard to believe. It was for me the first time I saw one as I had never maintained a DC10 beyond CAT II before I joined this operator. They were probably modified but to repeat myself the fleet was 100 plus strong and just about all CAT IIIa. I maintained them as so up until a few years ago when they were retired.

It must have been the -17's.

The bigger engine conversions were later.

I suspect that the Alaska 727-200ADV were part of the group of airplanes that Alaska got from Singapore 727-212ADV with the -17 engines. They were exceptionally well equipped with AT, ABS and believe auto speed brakes as well. High gross weight somewhere around 198K. Do not recall ever seeing an auto land option in the 727 but it might have been an option. Looking at My Boeing Fleet and it does not show up when doing a word search

Courtesy of smartcockpit.com, B727 Automatic Flight .

Looks like the 727 was capable with block V equipment.

OK456

Now that I think back, I seem to remember that on N2777 (or N27 ?), the -100 we got from the FAA, had an auto-land system installed for testing purposes. It was removed before we got the aircraft.

At least that was what we were told by someone from the FAA after we got the 727. Any truth to that rumor that you are aware of?

Spooky - I think our -200's w/-15 engines grossed out at around 196,000(??). I thought the AK's were much higher, like 208,000??


Research shows some topped out at 209,500. So 208,000 might have been close.


We didn't fly them anywhere near that weight, just DFW-SEA, so it was a reasonable weight and the improved performance of the -17's was noticeable.

That is most likely what I was thinking about. I know when we took it to Dalforth for the new cockpit that they pulled out hundreds of pounds of old wiring that had been install for test equipment back when the FAA had it.

What was interesting was the wiring was telephone wire.

Thanks for helping my memory, again. :p

On the autopilots, one Monday I took off and the autopilot paddles (switches) would not remain on. So I used a rubber band to keep the paddles connected for the week. For some reason maintenance could not fix it until the weekend. I don't have the foggiest why not. And to be honest I can't remember more than four or five times in ten years that we had autopilot problems with the 727s. So that's pretty good.

I don't recall seeing anything over 198K unless it was a Boeing built freighter like the Fed Ex model -200F. As recall there was a different structure that increased the empty weight significantly on those aircraft. Do not recall the MTOGW but 208, sounds a little heavy?


The Singapore -212ADV was a 198,000 airplane and that I'm pretty sure of as we bought one from AK and did a corporate conversion on it.

Max gross weight on the -17R powered 200 series went up to 209,500 pounds.

By chance do you recall who the operator(s) were that used those weights? I cannot find anything in My Boeing Fleet that talks to those weights but that does not mean that they don't exist.

For some reason American Airlines keeps popping up in my mind for the answer. I think they were the last passenger airlines to get the brand new 727-200 advanced versions.

Very possibly wrong on that.

At 209,000, it must have been every bit the slug w grossed out D-9 powered early -200 was. I can't remember the gross on those were, but it wasn't pretty on a warm day at gross.

GF

I know it wasn't AA. Suspect it had to be freighter as I pretty darn sure that weight was not available for a pax airplane unless in was a one-off corporate/government delivery. AS I mentioned earlier I can't find any reference to that weight in My Boeing Fleet and goes all the way back to the DC7C if you look hard enough:)

Not the Boeing DC-7C, successor to the Boeing DC-6 and DC-4? :p

GF

AA wasn't 209.500. I think the heaviest were 196,000(?).


I think the Alaska 727's we flew during the 'Alaska Airlines Interchange(?)' max'd out around 208,000. We didn't fly them that heavy so we just had the increased thrust to weight ratio of the -17(?) engines vs. the -15/15A engines. It was noticeable.


Trying to remember from 28-30 years ago...

Still better than the ex-Air France 727-200s with the -7 engines. Thank God I never had to fly one, but we almost leased one of them, until we found out that they had the -7 engines.

I can't imagine what a takeoff out of Denver on a summer day would have been like.

Back in the 80's AK was buying both used and factory new 727's. My only experience was the purchase of one of the former 727-212Avd airplanes they had bought from Singapore. Very low time and exceptionally well equipped. These were -17 powered and had a MGTOW or TAXI, can't recall which of 198,000. I believe SIA only had six of these in service.