B727-200 Autopilot
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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
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
Last edited by Vc10Tail; 30th Dec 2015 at 20:47. Reason: syntax
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 !
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 !
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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.
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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?
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?
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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).
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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?
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?
Miss Piggy had two square lights on the leftish (?) forward instrument panel, one red and one yellow, both of which were functional only with the A/P engaged (either SP-50 or SP-150).
The red one I believe was labeled SYS AB and was to warn if the hydraulic system in use by the A/P dropped below some threshold pressure (1/2 sys pressure or around 1500 psi I believe).
The light was deemed necessary because neither the block 50 nor 150 autopilots would disconnect automatically with hydraulic failure. The A/P would remain engaged electrically with all selected flight mode annunciations but would not be able to 'fly' the aircraft as such.
And the yellow one was the Stab Out of Trim light which is another story.
edit: As I recall now the red light was actually labelled 'Elevator Low Pressure' or something to that effect.
The red one I believe was labeled SYS AB and was to warn if the hydraulic system in use by the A/P dropped below some threshold pressure (1/2 sys pressure or around 1500 psi I believe).
The light was deemed necessary because neither the block 50 nor 150 autopilots would disconnect automatically with hydraulic failure. The A/P would remain engaged electrically with all selected flight mode annunciations but would not be able to 'fly' the aircraft as such.
And the yellow one was the Stab Out of Trim light which is another story.
edit: As I recall now the red light was actually labelled 'Elevator Low Pressure' or something to that effect.
Last edited by Vc10Tail; 1st Jan 2016 at 21:27.
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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 ?
Was that the same PDC that found its way into the 732-Advc ?
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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.
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grounded 27 do you know if yhose Cat3A approved planes were post 1984?
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Cheers
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.
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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.
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
GF
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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.
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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.
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.
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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(?).
-19(?) engines. Rocket ship. Huge improvement over the -15's(?).
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scream around the sky at high Mach
We really didn't care about fuel burn/cost. Taxpayers paid for the fuel.
Well actually they paid for everything.
grounded 27 do you know if yhose Cat3A approved planes were post 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
