On April 4^th 1979,  TWA 727 N840TW was operating as Flight 841 departing John F. Kennedy International Airport, New York (JFK), to Minneapolis St. Paul International Airport, Minnesota with 82 passengers and 7 crew.  It had an uncontrolled 34,000 foot dive. 

     As passengers were having cocktails at 39,000 feet above Siginaw, Michigan,  The TWA 727 they were in rolled right and started an uncontrolled decent in a steep spiral.  At Mach buffet,  the aircraft began to shed parts.  The passengers experienced up to 6G’s during the in flight upset before the flight crew was able to get the aircraft under control and back to level flight at 5,000 feet.  This 34,000 foot drop took 63 seconds which to it passengers seemed like an eternity.  The aircraft had a maximum speed of about 0.96 mach at 31,800 feet. The crew later landed at Detroit metro after discovering that they had damaged landing gear, a missing leading edge flap, flight spoiler, and other missing parts.

     It has been reported that the older 727 Captains would pop the circuit breaker for the leading edge slats and drop the flaps 2 degrees.  In the 727 the flaps extend rearward and do not start to drop down at flaps 2 degrees.  This increases the wing area with no added drag letting the pilot cruise higher by a couple thousand feet.  This was believed to save on fuel while adding a few precious knots to the cruise speed. 

     While Cruising at mach .816 at 39,000 feet pressure altitude and attempt was made to extend 2 degrees of the trailing edge flaps independently of the leading edge slats,  The Nos. 2, 3, 6 and 7 leading edge slats began to extend.  Two seconds later the aircraft began to buffet and roll slowly to the right.   Six to seven seconds later the roll rate began to increase do to increasing slat asymmetry as the Nos. 2,3 and 6 slats retracted.  The No. 7 slat failed to retract.

     While trying to figure out what was going on,  the aircraft entered a rapid right roll and the pilot applied full deflection of the lateral controls to stop the roll.  At this point the pilot pulled the throttles back to idle and deflected the rudder hard left.  In response to the hard deflection of the flight controls, The aircraft entered a substantial right sideslip.  The aircraft resumed right roll and began to descend rapidly and uncontrollably. The Captain extended speed brakes and detected no reaction and retracted them.  The aircraft completed a 360 degree roll while descending to around 21,000 feet.  The captain then had the first officer drop the gear to slow the aircraft down.  The aircraft continued to descend rapidly and continued to roll right until the No. 7 Slat was torn from the wing.  The captain was able to regain control of the aircraft at 5,000 feet. Minor injuries to 5 passengers were cause by the G-forces.

DAMAGE:

     The No. 7 leading edge slat on the right wing was missing, the outboard slat track was twisted and bent rearwards and the inboard track was bent rearward near the aft end of the track. The slat actuator cylinder was broken and the forward end of the actuator cylinder, the actuator piston and the piston rod were missing. The bolts that attached the slat to its track were sheared and the inboard fairing adjustment bolt was broken.  The skin of the lower surface of the wing aft of the No. 7 slat actuator was scraped and the 8 to 10 inch portion of the outboard aileron balance tab was missing at the end of the scrape mark.  The No. 10 flight spoiler panel was mostly missing and the inboard trailing edge flap track attachment bolts ere sheared and the carriage was damaged.  The main landing gear doors and their operating mechanisms were damaged extensively and a hydraulic line was ruptured. The sidebrace and actuator support beam on the right gear was broken and the uplock for the left gear was bent. The secondary wing skin panels about both actuator support beams were buckled upward. The No. 4 flight spoiler was torn around it actuator attachment point and fuel was leaking around several structural fasteners in the left wing.  Slight tension field wrinkles had formed in the fuselage skin fore and aft of the wing attachment areas.  The nose gear door was damaged and two blowout panels on the bottom of the No.3 engine support strut were missing.  Many passenger oxygen masks were hanging from their overhead compartments and an interior window was cracked.

The aircraft had a cockpit voice recorder (CVR) and it was undamaged. 21 minutes of the 30 minute tape were blank. The remaining 9 minutes of the tape had good fidelity but pertained only to the flightcrew conversations after the aircraft was on the ground at Detroit. Tests showed no discrepancies in the CVR’s electrical and recording systems.  The CVR can be bulk erased from the flightdeck after the aircraft was on the ground with its parking brake engaged, but the Captain stated that he usually activates the Bulk Erase feature at the conclusion of each flight but he could not recall having done so this time.  The rest of the flight crew stated that they did not erase the tape nor did they see the captain activate the erase button on the CVR control panel.