Wednesday, March 2, 2016

Reflecting on the Boeing 727

The first flight of the Boeing 727 began with a center-engine surge after takeoff.  It settled down quickly.  In any case, the tail-mounted configuration made engine-out handling much easier than wing-mounted engines. The outer leading-edge slats got stuck deployed (symmetric) as the aero loads overwhelmed the actuator.  It was going to take more than a few hiccups to keep Lew Wallick and his crew from two plus hours inflight, including landing configuration stalls, using flaps 40, using less than 2000 feet of ground roll in the first landing - and a big thumbs-up!  The first flight was on Feb. 9, 1963, fifty three years ago. I was almost five years old, living about 150 miles north in Vancouver and completely oblivious.  Yet my own personal first flight would be on a 727 just six years later.

The first 727 to enter revenue service was
N8107N, line 20, Eastern Airlines, on February 1, 1964, from Miami.                                  first Eastern 727 revenue flight

Eastern would take the first 757 revenue flight 19 years later, on January 1, 1983, out of Atlanta.

N7001U was delivered to United on June 10, 1964, and served until it was retired.

On Jan. 13, 1991, the airplane, having been repainted in its original United colors, flew revenue trip 838 SFO - SEA, then ferried to Boeing Field for an acceptance ceremony at the Museum, followed by its last flight, a ferry to Paine Field in Everett where the Museum has a restoration facility.

That very same first Boeing 727, N7001U, flew its last flight on March 2, 2016.  With flaps fixed at 15, and gear down, the minimum crew ferried the plane from Paine Field to Boeing Field, from which the Museum of Flight will have it for display.

The 767 had some hiccups too, like the landing gear slashing hydraulic lines when attempting to be raised in the first flight (Lew Wallick was there too), or the time the first 767 VA001 suffered full slat asymmetry and Tom Edmonds had to use full-wheel travel to compensate in the high speed landing.

The 727 line 2 "E2" N72700, was never delivered, but rather retained by Boeing until its demise in the late 1970s.  1832 were built, 1831 were delivered.  First jet to deliver over 1000, and the most popular jet in its time.

Boeing took possession of 727 line 117, originally delivered to Condor, and assigned N72700 registration.  I remember this airplane parked at Boeing field, and particularly for its use to take press photographers up to witness both the first 767 and the first 757 flights.

I was a Boeing avionics engineer starting with the 767 and 757 in 1981, while the 727 was still in production.   The 727 line ceased in 1984 at the time that the 737-300 and 747-300 programs had progressed.  I felt that the time to shut down the 727 had come with the 757 in hand, but it was odd with the 727-200F just getting certificated in 1983.

Boeing Field (July 1983).  RA001 (747), (?) 747, VA001 (767), ANA (767), NA002? (757), ? (737), first two Fedex 727-200F, ?737, E-3 AWACS

The loss of the 757 line still hurts.

I have long held that Frank Borman and Tex Boullioun opened the door for Airbus in the fateful conversation in Miami in August 1978, where Boeing offered 160 seat 727 replacement and Eastern wanted 175 seats. Borman says "if you will build it, I will buy it", and Boullioun responds "if you buy it, I will build it".

If only they had agreed to build a 160 seat 757-200 and followed a year later with a stretch 757-300 with 180 seats. Alas, Boeing left a gaping hole for about 150 seats, and Airbus was on the scene with the A320. The 757 never realized its destiny to inherit the route structures pioneered by the 727.

The Pratt and Whitney JT8D-1 marked the symbiotic relationship of building an engine and an airframe to match.  It used to take longer to build the engine than the airplane, leading engine manufacturers to think of the airframe as a subcontract.

Three 727 engines produced a maximum of 42,000 lbs thrust with the 727-100, and ended production with 52,200 lbs thrustfor a 210,000 lbs Advanced 727-200.

The 757-200 (220,000 lbs) started with about 74,000 lbs thrust and ended with about 86,000 lbs. thrust for a 273,000 lb 757-200.

A 220,000 lb 757-200 has over 21,000 lbs more thrust than a 210,000 Advanced 727-200.

With one engine failed, a 727-100 is down to 28,000 lbs thrust, a 757-200 down to 37,000 lbs. thrust.

Massive engines have taken twins to dominate even over four-engine wide-body long-haul. I was enthusiastic with the 747-8 development but wonder if cargo, passenger, government can sustain it. With big enough engines, the twins have won.
During certification testing in 2002, the GE90-115B engine set a world-record 127,900 lbs. of thrust. The GE90-115B ran for approximately 60 hours at triple red-line conditions (maximum fan speed, core speed and exhaust gas temperature) to evaluate the engine at its operational limits and demonstrate its capability beyond the most extreme operating conditions. GE90 - tested to 127,900 lbs of thrust  
The 747-100 entered service with four Pratt and Whitney JT9D-3A with a four-engine total of about 183,000 lbs of thrust.

Three engines could not compete with two really big engines.  With the 767 and 757 entering service by 1983, the 727 production ended in 1984. The Trijet era was over.

The 727 jet blast was over 100 mph 200 feet behind the airplane.

<place holder - flight deck and engineer>

The 757 was designed without a flight engineer.  The 767 went with two crew-members in a push to common type rating with the 757. The flight engineer was lost to automation. This became a big issue to me in 1990, for the B747-400 relied on ACARS to fill the gap.

Please - No Chemtrail comments!  NASA was curious about the wake vortex and installed smoke generators under the wingtips of a leased United 727.  Plus it reminded me of fuel jettison.

The 727 had the ability to dump fuel with wingtip nozzles.  There were a total of 8 fuel pumps, where the three engines can each draw from their own tank.  Fuel management was the task of the flight engineer. 727 Fuel System

Airplanes can be stretched by adding plugs to the cabin.  It is difficult to shrink an airplane, but it has been done (747SP).  Shrinking an airplane leaves much of it "over-built", hence not efficient.  It easier to add the bits and pieces to make it work as a more massive structure.

It is not feasible to change the width of the airplane.  All the Boeing narrow body sections were 12' 4" wide.

707 Cabin Fuselage 12' 4"

727 Cabin Fuselage 12' 4"

737 Cabin Fuselage 12' 4"

757 Cabin Fuselage 12' 4"

Airbus A-320  Cabin Fuselage 12' 11.5"

The 727 was the widest of the Boeing narrow-body cabins with 140" interior trim-to-trim, the rest were 139.3" (why?).

Airbus jumped on this making the A-320 about five inches wider than the 727.

727 Cabin Cross-section - 140" interior trim-to-trim

707 cross section - 139.3" interior trim-to-trim

737 cross section - 139.3" interior trim-to-trim

757 cross section - 139.3" interior trim-to-trim

Airbus A-320 cross section
143" useable coach cabin Vs Boeing 136"-138"

The 727 was the there at the birth of the trijets, later joined by the Lockheed L1011 and Douglas DC-10.

The Hawker Siddeley Trident flew in 1962, the first trijet and a bit ahead of the 727, ending production in 1978 with a little more than 100 delivered.  The Trident was designed to serve low-visibility landings.  Smiths was developing autoland for the Trident with a triple-redundant "brick-wall" autopilot. Elliot was developing a Vickers VC10 autoland at the same time using a dual-dual architecture.  In 1964 the Trident demonstrated autoland, with in-service autoland at Heathrow in 1965, achieving Cat IIIa certification in 1972, and Cat IIIb certification in 1975.

Coincidently, design of the Tupolev TU-154 started in 1963, first flight was in 1968 and it entered service in 1970.  Nearly 1,000 TU-154 were produced. The six-wheel main gear was an interesting feature.

The FAA exempted three-engine airplanes from the "60 minute" rule in 1964.  That gave an advantage to the Trijet.  This all happened with the 727 entry into service.


The Advanced 727-200 with all the options could fly 2,500 nm with a full load of passengers.
Advanced 727-200 JT8D-17R Engines Range Vs. Payload

The Advance 727-200 had three optional fuel tanks, effectively cargo pallets.  These could extend the range 250 miles.

Sea-level, standard-day maximum gross weight Advanced 727-200 (210,000 lb) takeoff
needs about a 9,600 foot runway.

The 727 has the lowest approach speed of ANY Boeing jet!
(including Douglas, from the 707 and DC-8 to the 787)                            approach speeds

Maximum gross weight landing, Advanced 727-200, sea level takes 4,600 feet of dry pavement.

Some 727's were equipped with nose gear brakes, which remains quite unique.

There are three hydraulic systems.

  • A is driven by two engine driven pumps.  
  • B is driven by two electric pumps.  
  • C uses an electric pump driven by standby power.  
  • A and B sides each have a redundant pump.  
  • The A reservoir fills the separate B and C (standby) reservoirs.

Primary Flight controls:

  • Elevator powered from either A or B
    • manual control (trim tab) reversion
  • Ailerons powered from either A or B
    • direct manual control reversion
  • Rudder is split into two surfaces:
    • Lower on A with dedicated standby power driven pump as backup
    • Upper on B

Secondary Flight Controls:

  • Stabilizer dual-electric motor driven (jack screw)
    • manual (cable) drive reversion
  • Leading edge on A
    • C backup (extend only)
  • Trailing edge on A
    • dedicated electric backup
  • Spoilers
    • outboard on A
    • inboard on B
    • ground on A
  • Yaw Dampers
    • Dual independent 
    • Valves in each of the upper/lower rudder hydraulic actuators


  • Nose gear brakes and steering on A
    • antiskid
  • Main brakes on B 
    • some way of switching in A
    • hydraulic accumulator
    • antiskid
    • pneumatic backup
  • Gear up/down on A
    • manual handcrank to each gear

Autopilot was a Sperry single-channel SP50 which provided roll and pitch control including approach mode.
In October 1976, Notice N 8400.18, Job Function Reference Guide for Air Carrier Safety Inspectors (OPERATIONS), was issued to establish approval criteria for FP CAT IIIa autoland operations using DH 50/RVR 700. In December 1976, the B-727 became the first airplane certificated by the United States for FP CAT IIIa operations. AC 120-28B, issued in December 1977, permitted CAT IIIa operations at runways equipped with suitably modified Type II ILS equipment. It also permitted FP autoland operations with aircraft having handling characteristics, physical characteristics, and seeing-conditions equivalent to the B-727 and DC-9 airplanes.

Alaska used a HUD to gain Cat IIIa approval.

In 1978, Boeing contracted with Smiths for a dual-servo autothrottle for the 727.
The autothrottle uses data from the Lear Siegler performance data com- puter (PDC)—a standard advisory system which tells the pilot the optimum altitude and airspeed for his flight—to drive the throttles via servos. The throttle computer is used to control airspeed through the auto- pilot and attitude on the flight direc- tor. In this fully integrated flight management system an energy method is used—if the airspeed is re- duced, say by a gust or weather change, the extra speed is converted into height. This gives the best flight profile without a lot of throttle move- ments, which decrease engine life and waste fuel. A feature of the STS-10 is that each engine is controlled separately to give its best engine pressure ratio (EPR) —engines behave slightly differently according to age, time since last over- haul and control-run differences.

The 727 was the first Boeing airplane to have an auxiliary power unit (APU).  The APU could deliver air conditioning, electricity, and engine start.  The APU was only used on the ground - being a Trijet after all.  The intake was in the left wheel well. The exhaust on the top of the airplane.

The model 727, which was originally fatigue tested to its Design Service Objective of 60,000 flight cycles. In order to stay ahead of the fleet leaders in terms of flight cycles, an in-service 727 airplane with 47,000 accumulated flight cycles was acquired, and the fuselage was cyclic pressure tested for an additional 76,000 cycles

The 727 had a tail skid to minimize damage in the event of over-rotation or landing too-high an attitude.   Not sure, but I assume this is a minimum unstick test, to prove the airplane can still take off if the pilot over-rotates.  In the testing I was aware of, Boeing used a wood-skid to avoid damaging the airplane, but here it looks like they are on the skid itself (not really sure).  This is N72700, I assume line number 2 "E2".

The "Flying Cuisinart"
(I attributed to Dale Ranz who was referring to 7J7, but not sure who was the originator)
In the mid 1980s, Boeing used a company-owned 727 to test a new engine for a proposed twin propeller-turbine transport that was to be designated the Model 7-J-7. A prototype General Electric GE-36 UDF (unducted fan or propfan) engine was mounted on the right rear side in place of the standard turbo jet engine. The UDF engine was a hybrid between a turbofan and a turboprop. It had a significant weight reduction and a 45% increase in fuel efficiency, however, Boeing did not develop the 7-J-7 that was used to test it.

The 727-200 had an option for rocket assisted takeoff (RATO) or jet assisted takeoff (JATO)  This was used in case an engine failed after rotation speed at a high density airport.

Watch the video and listen to the narration---> Youtube - 727 Rocket/Jet Assisted Takeoff

The 727 was the fastest Boeing jet with a Vmo of 390 kts, fully 15 kts faster than the 747. Only the 747 Mmo of 0,92 was faster than the 727 Mmo of 0.90.  The 757/767 twin jets used much less fuel. But they gave up a bit in speed.  The 757/767 are 360 kts, 0.86 Mach.

Three models were built: 727-100/100C, 727-200, 727-200F.

The first type, 727, was certificated on December 24, 1963 - Christmas Eve.

727C   January 13, 1966
727-200      November 29, 1967 (which brought 727-100, 727-100C)
727-200F    June 22, 1983

The ventral stairway, or aft stairway allowed for loading the airplane without any ramp assistance.  With the APU, the 727 could land anywhere (no wing-mounted engines helps too), remain comfortable in the cabin, load the passengers, and start the engines.

On November 24, 1971, DB Cooper hijacked a Northwest 727 and parachuted out the ventral stairway with $200,000, never to be seen or heard from again.

In 2003, a 727 was stolen and disappeared, never to be seen from again.

The 727 appeared in some form in about 200 movies. Here, from Firefox, using its acting skills, a 727 pretends to be a TU-154.

Bruce Campbell spends half of each year living in a Boeing 727 situated in the middle of the woods.

A T-tail is normally in the free-stream.  Under extreme angle-of-attack "deep stall", the airflow over the wing may "push the tail down", effectively causing a pitch up moment or blanking the tail altogether.  The 727 can encounter this, but only if forced.
there was some lateral control effectiveness still available and Lew used what there was to rock the airplane to increasingly higher bank angles until the nose finally fell through and normal control response was recovered.

My first assignment on the 757/767 was Pitch Augmentation Control System (PACS). The low tail (not the T-tail) would encounter the wing down-wash and cause a pitch-up moment approaching stall.  The flight rules did not originally permit the pilot to reverse pitch commands entering a stall and the pitch-up moment created such a scenario.  PACS was a dual system that provided an offset in stabilizer trim to artificially keep the pilot from releasing the column entering a stall.  PACS was replaced on both the 757 and 767 with vortex generators, which shifted the lift outboard on the wing (by pumping energy into the boundary layer along the outboard leading edge) at high angle-of-attack creating sufficient pitch-down to be acceptable (the lift is lost first near the root shifting the center of lift aft due to wing sweep).  The dual computer system was replaced with 14 pieces of aluminum, and I moved to Thrust  Management Systems (which used the same General Electric computing platform) in 1982.

The Discovery channel deliberately crashed a 727 in 2012, as part of a television show. 

Triple-slotted fowler flaps proved to be remarkably effective.

Five airplanes crashed the first few years of 727 entry into service where excessive sink rate may have been a contributing factor coupled with unfamiliarity with sluggish turbine spool up time compared to piston-powers airplanes. Flaps 40 got a bad reputation, and flight idle plus 8 seconds to go-around power was the rule (25.119).

August 16, 1965 United Airlines Flight 389 (Lake Michigan)

November 8, 1965 American Airlines Flight 383 (Cincinnati)

November 11, 1965 United Airlines Flight 227 (Salt Lake City)

February 4, 1966  All Nippon Airways Flight 60 (Tokyo Bay)

November 15, 1966  Pan Am 708 (Berlin)

Peter Lemme

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