# Accident 19980521015609A: Doug DC1010, Los Angeles, CA, May 21, 1998 - Type: FAA accident report (Accident/Incident Data System), as reported - Date: May 21, 1998, 13:05 local time - Place: Los Angeles, CA - Airport: Los Angeles International - Phase of flight: Normal Cruise - Operating rules: Air carrier (Part 121) - Operator: CALA - Location: 33.9497° N, 118.4000° W: From the FAA, an estimate near the named town, within about 3 miles - Nearby events: https://openairdocs.org/map.md?lat=33.9497&lon=-118.4000&mi=10 - Aircraft: N68043, a cancelled registration (https://openairdocs.org/deregistered/N68043-2018-05-31) (OpenAirDocs) - Registry model: Mcdonnell Douglas DC-10-10 (registry code 3022110, https://openairdocs.org/model/mcdonnell-douglas-dc-10-10) (OpenAirDocs) - Registry engine: GE CF6-6 series (registry code 30020, https://openairdocs.org/engine/ge-cf6-6-series) (OpenAirDocs) - Reported make and model: DOUG DC1010 - Reported engine: GE CF66D - People aboard: 290 - Fatal injuries: 0 - Pilot flight hours: 17,000 total, 9,000 in this make and model, 79 in the last 90 days - NTSB investigation: [NTSB LAX98FA169](https://openairdocs.org/ntsb/LAX98FA169) (OpenAirDocs) - FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/) - Page: https://openairdocs.org/incident/19980521015609A ## Narrative As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^. SMOOTH AIR AUTOPILOT ON. PITCHED UP SUDDENLY. CUTOFF AUTO PILOT. PUT NOSE DOWN. CREW AND PASSENGER INJURY. SIGN ON. (.4)THE AIRCRAFT WAS CLIMBING IN SMOOTH AIR ABOUT 500 FEET PER MINUTE WITH THE NO. 1 AUTOPILOT ENGAGED. THE CAPTAIN REPORTED THAT THE AIRCRAFT BEGAN A SUDDEN AND HARD UNCOMMANDED 2G PULL-UP, WITH THE CONTROL YOKE MOVING RAPIDLY AFT. HE IMMEDIATELY GRABBED THE CONTROL YOKE, DISENGAGED THE AUTOPILOT, AND LEVELED THE AIRCRAFT. THREE FLIGHT ATTENDANTS IN THE AFT GALLEY AND ONE PASSENGER IN AN AFT LAVATORY SUSTAINED SERIOUS INJURIES. THE AFT GALLEY FLIGHT ATTENDANTS DESCRIBED THE ONSET OF THE EVENT AS 'BEING PULLED TO THE FLOOR BY WHAT FELT LIKE A STRONG PULL OF GRAVITY.' THE FORCE SUDDENLY REVERSED AND THE THREE WERE 'THROWN UP INTO THE CEILING.' ANOTHER FORCE REVERSAL FOLLOWED AND THE THREE WERE 'SLAMMED DOWN AGAINST THE FLOOR.' THE FLIGHT ATTENDANTS SAID THAT A 'ROLLER COASTER' TYPE MOVEMENT THEN OCCURRED, WHICH QUICKLY DAMPED INTO A STEADY STATE. REVIEW OF THE AIRCRAFT'S MAINTENANCE RECORDS FOR THE YEAR PRECEDING THE ACCIDENT REVEALED OVER 50 DISCREPANCIES FOR AUTOPILOT SYSTEM UNCOMMANDED DISCONNECTS, UNCOMMANDED PITCH-UPS, AND FAILURES TO ENGAGE. REVEIW OF THE DFDR DATA REVEALED THAT AS THE AIRCRAFT PASSED THROUGH 29,200 FEET, FOUR PITCH CYCLES WERE REOCRDED OVER A 15-SECOND TIME PERIOD AND WERE ACCOMPANIED BY WERTICAL ACCELERATIONS, THE MOST SEVERE OF WHICH WAS BETWEEN 1.84 AND -0.12 G'S. THE INITIAL UNCOMMANDED NOSE PITCH-UP WAS PRECEDED BY AN AUTOPILOT CONTROLLED MOVEMENT OF THE LEFT INBOARD ELEVATOR. THE SUBSEQUENT ELEVATOR MOVEMENTS ANF RESULTANT PITCH EXCURSIONS WERE DUE TO THE PILOT'S CONTROL INPUTS. WITH THE EXCEPTION OF THE CAPTAIN'S ANF FIRST OFFICER'S CONTROL WHEEL SENSOR UNITS, ALL AUTOPILOT SYSTEMS PASSED FUNCTIONAL CHECKS. POSTACCIDENT TEST OF THE FIRST OFFICER'S CONTROL WHEEL SENSOR UNITS SHOWED AN OUT OF TOLERANCE AND DRIFTING NULL SIGNAL FOR THE STRAIN GAGE WHICH PROVIDES PITCH SIGNAL INPUT TO THE NO. 1 AUTOPILOT. AFTER ABOUT 3 MINUTES, THE SIGNAL BECAME NOISY AND JUMPED TO VALUES OF UP TO 4 VOLTS SEVERAL TIMES. MANY SPIKES WERE ALSO OBSERVED AT VALUES UNDER 3.5 VOLTS (SIGNALS OVER 3.5 VOLTS TRIGGER AN AUTOMATIC DISENGAGEMENT OF THE AUTOPILOT). SUBSEQUENT EXAMINATION OF THE PITCH STRAIN GAGES BY OPTICAL MAGNIFICATION FOUND A FOREIGN BLACK-GRAY METALLIC-LIKE SUBSTANCE BRIDGING TH E TERMINAL LUG ENDS. ANALYSIS SHOWED THE MATERIAL WAS A SILVER BASED CONDUCTIVE SUBSTANCE, LYING BELOW A FACTORY APPLIED SEALING LAYER, WHICH WAS INTRODUCED DURING MANUFACTURE. THE SOLDER ON THE LUGS AND THE WIRE USED BETWEEN THE LUGS AND TERMINALS WAS FOUND NOT TO BE CONSISTENT WITH THE MANUFACTURER'S SPECIFICATIONS. (-23)DURING INTERVIEW, ^PRIVACY DATA ^STATED THAT #1 AUTOPILOT WAS ENGAGED, SEAT BELT SIGN STILL ILLUMINATED, AIRCRAFT WAS CLIMBING TO FL 330, AND FLIGHT CONDITIONS WERE VMC AND SMOOTH. AT APPROXIMATELY FL 310 THE AIRCRAFT PITCHED UP RAPIDLY WITH SIMULTANEOUS AFT CONTROL YOKE MOVEMENT. ^PRIVACY DATA ^ ESTIMATED APPROXIMATELY A +2 G PITCH UP, ALTITUDE GAIN OF 1,000 TO 1200 FEET, AND A LOSS OF APPROXIMATLEY 30 KNOTS AIRSPEED. ^PRIVACY DATA ^ COUNTERED THE AFT YOKE MOVEMENT, DISENGAGED THE AUTOPILOT, AND SLOWLY RECOVERED THE AIRCRAFT ATTEMPTING TO MINIMIZE NEGATIVE G'S. HE STATED THE AIRCRAFT WAS INTRIM, AUTOTHROTTLES STABLE IN CLIMB POWER, AND FIGHT CONDITIONS WERE SMOOTH AFTER PITCH UP. HE NOTED NO WIND VELOCITY OR DIRECTION CHANGE ON THE LONG RANGE NAVIGATION WIND READ OUT THAT WOULD INDICATE THA THE PITCH UP WAS CAUSED BY CLEAR AIR TURBULENCE. ## The NTSB's investigation of this event (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB LAX98FA169](https://openairdocs.org/ntsb/LAX98FA169), May 21, 1998: McDonnell Douglas DC-10-10 (N68043), Los Angeles, CA, no damage. Probable cause: The contaminated strain gage, which resulted in shorting of the strain gage's terminal lugs which lead to excessive autopilot initiated elevator movement, and excessive elevator actuation during… ## Other reports on N68043 (8) Matched to the same aircraft by N-number and date. - [Incident 19910713040289I](https://openairdocs.org/incident/19910713040289I), Jul 13, 1991: Doug DC1010 (N68043), Honolulu, HI, Minor damage. Vibration on climbout. Dumped fuel and returned. Found first stage fan blades damaged. - [Incident 19890330015269I](https://openairdocs.org/incident/19890330015269I), Mar 30, 1989: Doug DC1010 (N68043), Agana, Guam. NR2 engine manifold failed light on. Shut down pneumatic system. Returned. Overheat detector was inoperative. - [Incident 19871214081539I](https://openairdocs.org/incident/19871214081539I), Dec 14, 1987: Doug DC1010 (N68043), Honolulu, HI. Observed to be right of track. Crew action caused ins to slip to heading mode thereby not flying predetermined route - [Accident 19861107086119A](https://openairdocs.org/incident/19861107086119A), Nov 7, 1986: Doug DC1010 (N68043), Los Angeles, CA. The aircraft pitched abruptly up and down causing injuries. The number 2 autopilot pitch sensor found to be faulty - [Incident 19850718046189I](https://openairdocs.org/incident/19850718046189I), Jul 18, 1985: Doug DC1010 (N68043), Houston, TX, Minor damage. Nose pitched up when main gear touched and tail struck runway. Unqualified flight engineer made the landing. - [Incident 19850706038389I](https://openairdocs.org/incident/19850706038389I), Jul 6, 1985: Doug DC1010 (N68043), Chicago, IL. Left main gear tires went flat as turn was being made to taxiway. No mechanical malfunctions found. - [Incident 19830604071389I](https://openairdocs.org/incident/19830604071389I), Jun 4, 1983: Doug DC1010 (N68043), Yuma, AZ. Rapid nose down pitch followed by a pitch up. Autopilot disengaged. Had an autopilot malfunction. Cause undetermined. - [Incident 19800302029819I](https://openairdocs.org/incident/19800302029819I), Mar 2, 1980: Doug DC1010 (N68043), Houston, TX. Pilot took evasive action during landing roll to avoid an aircraft holding at a taxiway intersection. From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.