Looking at cutaway drawings of the Boeing 707, it appears that this aircraft did not have split rudders like the Boeing 727 and that it had a single rudder actuator system. Of course cutaway drawings don't show everything. Since I don't have detailed schematics of the Boeing 707 and its civil and military siblings, I don't know how the rudder system functioned.

According to Wikipedia, which is not always all that reliable, the 737 had a single hydraulic Power Control Unit specifically designed for that plane by Boeing and built to spec by Parker Hanifin. If the Boeing 707 had a reliable rudder system, why didn't Boeing just export and downsize that design to the 37? I am assuming, perhaps falsely that Boeing did not feel like the Split Rudder design on the 27 was feasible on the 37 for economic or other reasons. Can anyone supply any useful information on this . . . perhaps a mechanic who worked on rudders for the 707 or its civil or military brothers?

Perhaps the 707 had rudder issues to which I am not familiar?

convair880mfan wrote:

Looking at cutaway drawings of the Boeing 707, it appears that this aircraft did not have split rudders like the Boeing 727 and that it had a single rudder actuator system. Of course cutaway drawings don't show everything. Since I don't have detailed schematics of the Boeing 707 and its civil and military siblings, I don't know how the rudder system functioned.

According to Wikipedia, which is not always all that reliable, the 737 had a single hydraulic Power Control Unit specifically designed for that plane by Boeing and built to spec by Parker Hanifin. If the Boeing 707 had a reliable rudder system, why didn't Boeing just export and downsize that design to the 37? I am assuming, perhaps falsely that Boeing did not feel like the Split Rudder design on the 27 was feasible on the 37 for economic or other reasons. Can anyone supply any useful information on this . . . perhaps a mechanic who worked on rudders for the 707 or its civil or military brothers?

Perhaps the 707 had rudder issues to which I am not familiar?

Does the 707 not have a manual / cable rather than hydraulically actuated?

I found this old thread

viewtopic.php?t=741277

Thanks for all that information!

Am still a bit in the dark about whether the 707 had a single or dual rudders, a single or dual rudder actuators . . . if anyone can help there.

It seems that the rudder on the 707 was aerodynamically balanced and actuated by means of cable-controlled tabs and incorporated systems for both manual and hydraulic actuation, hydraulic power used to assist in rudder deflection. Would that mean that the 707 could only experience "rudder reversal' if a cable broke or a malfunction of the auxiliary hydraulic system which powered it or some component in the system such as in the yaw damper or actuator system? Sorry if I am phrasing this badly. I am not a technician or engineer.

Also still in the dark as to why Boeing developed a new device for the 737 rudder system [the Paker Hanifin manufactured PCU] if the old 707 system was still good as in "if it ain't broke, don't fix it."? Sorry about the grammar there.

Thanks for all that information!

Am still a bit in the dark about whether the 707 had a single or dual rudders, a single or dual rudder actuators . . . if anyone can help there.

It seems that the rudder on the 707 was aerodynamically balanced and actuated by means of cable-controlled tabs and incorporated systems for both manual and hydraulic actuation, hydraulic power used to assist in rudder deflection. Would that mean that the 707 could only experience "rudder reversal' if a cable broke or a malfunction of the auxiliary hydraulic system which powered it or some component in the system such as in the yaw damper or actuator system? Sorry if I am phrasing this badly. I am not a technician or engineer.

Also still in the dark as to why Boeing developed a new device for the 737 rudder system [the Paker Hanifin manufactured PCU] if the old 707 system was still good as in "if it ain't broke, don't fix it."? Sorry about the grammar there.

Near as I can gather, the B707 has a single rudder with a single power pack, or power control actuator, with manual reversion.

Take a look at this accident report, starting on page 19.

https://www.fss.aero/accident-reports/d ... -26-US.pdf

As to why the B707 didn’t suffer the same rudder PCA issues as the early B737…different systems, different actuators. As I recall, the problem in the B737 was the actuator itself, and not the aircraft systems, per se. But, truth is, I’ve never really looked into those issues.

convair880mfan wrote:

Looking at cutaway drawings of the Boeing 707, it appears that this aircraft did not have split rudders like the Boeing 727 and that it had a single rudder actuator system. Of course cutaway drawings don't show everything. Since I don't have detailed schematics of the Boeing 707 and its civil and military siblings, I don't know how the rudder system functioned.

According to Wikipedia, which is not always all that reliable, the 737 had a single hydraulic Power Control Unit specifically designed for that plane by Boeing and built to spec by Parker Hanifin. If the Boeing 707 had a reliable rudder system, why didn't Boeing just export and downsize that design to the 37? I am assuming, perhaps falsely that Boeing did not feel like the Split Rudder design on the 27 was feasible on the 37 for economic or other reasons. Can anyone supply any useful information on this . . . perhaps a mechanic who worked on rudders for the 707 or its civil or military brothers?

Perhaps the 707 had rudder issues to which I am not familiar?

The birth of the 737 was a rush job, is essentially your answer:

https://special.seattletimes.com/o/news ... index.html

"It would take four spectacular crashes and an alert United pilot catching a PCU defect on the ground to focus concern on malfunctions of the power-control unit."
Can anyone expound on the alert United pilot and that part of the story?

After reading that, it makes me wonder how far back you have to go to encounter a Boeing that was worth a $hit. So immoral, so unthetical, so...well words,
any words, fail to accurately describe what they were - and still are.

The link goes to a 6 part news story and expounds on the UAL pilot’s story.

Thanks, I did not see the drop down menu at the top - doh!

I believe the UAL pilot account is in part 2 under the section header called “crash in Panama, alert pilot in Chicago” around the middle of the article

It’s about 4 paragraphs worth of blurb.

Only problem the 707 rudder had was with the CFM powered versions which had flutter issues. This was applicable to the full size, not the KC-135-sized airplanes.

Link

The original issue with the 707 rudder on the short-fin models was that it required something like 100 lb of force to move, which is why they added the taller fin, ventral fin, and boost: https://airlinercafe.com/page.php?id=72

I believe the UK regulators were going to refuse certification if they didn't address that. The control system for it is nifty as well: http://adastron.com/707/qantas/Q-bellows.htm

Thank you all for such wonderful information. I am most appreciative of your efforts!

I believe Boeing deserves all the flak they can get for their behaviour the last couple of decades. But. It took a whole lot of smart people in and out of Boeing a whole lot of years to find out what if anything was wrong with those rudders. This was no «uncovering the dark secret of the evil shortcut»-story like the MCAS debacle.
It was a real mystery.

AvgWhiteGuy wrote:

"It would take four spectacular crashes and an alert United pilot catching a PCU defect on the ground to focus concern on malfunctions of the power-control unit."
Can anyone expound on the alert United pilot and that part of the story?

After reading that, it makes me wonder how far back you have to go to encounter a Boeing that was worth a $hit. So immoral, so unthetical, so...well words,
any words, fail to accurately describe what they were - and still are.

LH707330 wrote:

The original issue with the 707 rudder on the short-fin models was that it required something like 100 lb of force to move, which is why they added the taller fin, ventral fin, and boost: https://airlinercafe.com/page.php?id=72

I believe the UK regulators were going to refuse certification if they didn't address that. The control system for it is nifty as well: http://adastron.com/707/qantas/Q-bellows.htm

They did indeed, and as a result Boeing had to back to the drawing board. It was the same CAA airman who refused to sign off on the 727 and 737, and also the same guy who said the first time Boeing built a really good aircraft was the 747. Mind, he wasn’t afraid to criticise home-grown aircraft either, and readily ripped the Trident apart.

Google D.P. Davies for more information, or enjoy these podcasts:

https://www.aerosociety.com/news/audio- ... -brabazon/
https://www.aerosociety.com/news/audio- ... oeing-727/

BP Davies was the quintessential test pilot and the epitome of good airmanship


‘Handling the big jets’ was and still is the Bible for jet transport operation


I wish someone would write an updated version combining Davies’ invaluable engineering, aerodynamic and handling advice with insights on the intricacies of operating todays highly automated aircraft and the advantages/ pitfalls of FBW

Max Q wrote:

BP Davies was the quintessential test pilot and the epitome of good airmanship


‘Handling the big jets’ was and still is the Bible for jet transport operation


I wish someone would write an updated version combining Davies’ invaluable engineering, aerodynamic and handling advice with insights on the intricacies of operating todays highly automated aircraft and the advantages/ pitfalls of FBW

An amazing book that I bulled my way through before my ATPL course. Tough going at times for my level at the time, but it definitely paid off.

While we wait for an updated version, Automation Airmanship is a good read.



https://www.goodreads.com/book/show/197 ... airmanship

Aaron747 wrote:

convair880mfan wrote:

Looking at cutaway drawings of the Boeing 707, it appears that this aircraft did not have split rudders like the Boeing 727 and that it had a single rudder actuator system. Of course cutaway drawings don't show everything. Since I don't have detailed schematics of the Boeing 707 and its civil and military siblings, I don't know how the rudder system functioned.

According to Wikipedia, which is not always all that reliable, the 737 had a single hydraulic Power Control Unit specifically designed for that plane by Boeing and built to spec by Parker Hanifin. If the Boeing 707 had a reliable rudder system, why didn't Boeing just export and downsize that design to the 37? I am assuming, perhaps falsely that Boeing did not feel like the Split Rudder design on the 27 was feasible on the 37 for economic or other reasons. Can anyone supply any useful information on this . . . perhaps a mechanic who worked on rudders for the 707 or its civil or military brothers?

Perhaps the 707 had rudder issues to which I am not familiar?

The birth of the 737 was a rush job, is essentially your answer:

https://special.seattletimes.com/o/news ... index.html

Wow, thanks for that link. So many similar attitudes/statements between then and 2019....

Starlionblue wrote:

Max Q wrote:

BP Davies was the quintessential test pilot and the epitome of good airmanship


‘Handling the big jets’ was and still is the Bible for jet transport operation


I wish someone would write an updated version combining Davies’ invaluable engineering, aerodynamic and handling advice with insights on the intricacies of operating todays highly automated aircraft and the advantages/ pitfalls of FBW

An amazing book that I bulled my way through before my ATPL course. Tough going at times for my level at the time, but it definitely paid off.

While we wait for an updated version, Automation Airmanship is a good read.



https://www.goodreads.com/book/show/197 ... airmanship

Thanks for that, I’ll check it out

M564038 wrote:

I believe Boeing deserves all the flak they can get for their behaviour the last couple of decades. But. It took a whole lot of smart people in and out of Boeing a whole lot of years to find out what if anything was wrong with those rudders. This was no «uncovering the dark secret of the evil shortcut»-story like the MCAS debacle.
It was a real mystery.

It would have been less of a mystery if it wasn't a POS design that was allowed to live on through updating type certificates to add new variants. Had it not been grandfathered in, that would not have been acceptable as a new design in the early 80s.

There were more 737 Jurassics and Classics built and they racked up significantly more cycles than the 707. Even if the 707 had the same issue, it would be more likely to occur on a 737.

There were a few 707s that went over 100K cycles. The DSO was 20K, I believe.

B777LRF wrote:

LH707330 wrote:

The original issue with the 707 rudder on the short-fin models was that it required something like 100 lb of force to move, which is why they added the taller fin, ventral fin, and boost: https://airlinercafe.com/page.php?id=72

I believe the UK regulators were going to refuse certification if they didn't address that. The control system for it is nifty as well: http://adastron.com/707/qantas/Q-bellows.htm

They did indeed, and as a result Boeing had to back to the drawing board. It was the same CAA airman who refused to sign off on the 727 and 737, and also the same guy who said the first time Boeing built a really good aircraft was the 747. Mind, he wasn’t afraid to criticise home-grown aircraft either, and readily ripped the Trident apart.

Google D.P. Davies for more information, or enjoy these podcasts:

https://www.aerosociety.com/news/audio- ... -brabazon/
https://www.aerosociety.com/news/audio- ... oeing-727/

Thanks for those links, gotta go check them out. Handling the Big Jets is a great read, I really enjoyed that one.

Makes one wonder, did Douglas have major issues with the DC-8 EIS beside the higher-drag wingtips that they fixed relatively quickly?

Max Q wrote:

Starlionblue wrote:

Max Q wrote:

BP Davies was the quintessential test pilot and the epitome of good airmanship


‘Handling the big jets’ was and still is the Bible for jet transport operation


I wish someone would write an updated version combining Davies’ invaluable engineering, aerodynamic and handling advice with insights on the intricacies of operating todays highly automated aircraft and the advantages/ pitfalls of FBW

An amazing book that I bulled my way through before my ATPL course. Tough going at times for my level at the time, but it definitely paid off.

While we wait for an updated version, Automation Airmanship is a good read.



https://www.goodreads.com/book/show/197 ... airmanship

Thanks for that, I’ll check it out

Same, gotta go read that one soon!

extender wrote:

There were a few 707s that went over 100K cycles. The DSO was 20K, I believe.

Cycles or hours ?!

Cycles

The issue was with the actuator that Parker built, not the design of the airplane itself.

extender wrote:

Cycles

That’s very difficult to believe

Max Q wrote:

extender wrote:

Cycles

That’s very difficult to believe

N131EA, was operated by Boeing as a TC-18E. It was flying out of Tinker as a trainer for the E-3 Sentry. This particular airplane, I remember seeing some induction paperwork with the times and cycles. It along with its sister N132EA visited MIA for MRO work. Incredible? I know where you're coming from.

This came up in a search:

viewtopic.php?t=437247

[threeid][/threeid]

extender wrote:

Max Q wrote:

extender wrote:

Cycles

That’s very difficult to believe

N131EA, was operated by Boeing as a TC-18E. It was flying out of Tinker as a trainer for the E-3 Sentry. This particular airplane, I remember seeing some induction paperwork with the times and cycles. It along with its sister N132EA visited MIA for MRO work. Incredible? I know where you're coming from.

This came up in a search:

viewtopic.php?t=437247

I see several aircraft mentioned with well over 100,000 hours but I don’t see any details about a 707 with over 100K cycles, it doesn’t sound right


The DC9 is the only type I know that came remotely close to that mark with one example reaching close to 90K cycles



But that type was used intensively in short haul ops and had an airframe optimized for that

There was this thread that mentions a Westjet 737-200 that accumulated over 97,000 cycles. viewtopic.php?t=1390723

That’s a pointless distinction. That actuator wasn’t some off the shelf customer option, but built for, because of, and as an integral non-replacable part of the 737.

N1120A wrote:

The issue was with the actuator that Parker built, not the design of the airplane itself.

M564038 wrote:

That’s a pointless distinction. That actuator wasn’t some off the shelf customer option, but built for, because of, and as an integral non-replacable part of the 737.

N1120A wrote:

The issue was with the actuator that Parker built, not the design of the airplane itself.

But one that was designed and made by a company other than Boeing - just like an engine that fails.

Max Q wrote:

I see several aircraft mentioned with well over 100,000 hours but I don’t see any details about a 707 with over 100K cycles, it doesn’t sound right.

Max, I get where you are coming from, but these things were crashing and dashing at Tinker all day long. All I can tell you is what I remember seeing, and I do know the difference between time and cycles. I deal with them constantly.

N1120A wrote:

M564038 wrote:

That’s a pointless distinction. That actuator wasn’t some off the shelf customer option, but built for, because of, and as an integral non-replacable part of the 737.

N1120A wrote:

The issue was with the actuator that Parker built, not the design of the airplane itself.

But one that was designed and made by a company other than Boeing - just like an engine that fails.

I had an impression that was Boeing design outsourced to parker for manufacturing?

Aaron747 wrote:

The birth of the 737 was a rush job, is essentially your answer:

https://special.seattletimes.com/o/news ... index.html

That makes the fact that they even built the MAX in the first place even worse.

An American Airlines 707 rolled inverted and crashed after takeoff out of JFK, killing all 95 onboard. Flight was AA1 to Los Angeles, March 1, 1962. Ship was N7506A, a 707-123B. The crash was even used as a plot point in the TV show Mad Men.

Cause of the crash? Rudder hardover.

AA1 rudder hardover was very different in cause than the B737 problem, unrelated.

To be specific, the cause of the AA1 crash was a yaw damper hard-over, caused by an electrical short in a wiring bundle that was damaged in manufacturing.

The yaw damper only has partial range of rudder control, and can be overridden by the rudder pedals through the rudder clutch assembly. Also can be disabled through a switch. But the upset ocurred right after takeoff with little time or altitude available for recovery. The pilots did execute the recovery procedure right up to the moment of impact.

A true rudder hard-over at that altitude would be much more severe and completely unrecoverable. Basically an immediate inversion and impact.