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A C340 in cruise at FL210 experienced a frozen elevator trim control caused by the incorrect jackscrew lubricant.
| Attributes | |
| ACN | 398532 |
| Time | |
| Date | 199804 |
| Day | Sat |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : eni |
| State Reference | CA |
| Altitude | msl bound lower : 21000 msl bound upper : 21000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa |
| Operator | general aviation : personal |
| Make Model Name | Cessna 340/340A |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise other descent : approach descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 28 flight time total : 2937 flight time type : 800 |
| ASRS Report | 398532 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Events | |
| Anomaly | aircraft equipment problem : critical non adherence : published procedure non adherence : far other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem none taken : anomaly accepted |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
Flight from O48 to smo, altitude FL210. Route O48-eni-direct avenal-fernando 5 arrival smo. Problem: after leveling at FL210, noted elevator trim was frozen. Pulled elevator trim circuit breaker -- no effect. It was necessary to fly with moderate forward pressure on yoke. Until I adjusted to this, altitude varied +/-200 ft. Approximately 50 NM from filmore, was instructed to cross 10 NM northwest of filmore at 11000 ft. I notified center (ZLA) few mins later of amount of forward pressure needed and nose was bobbing up and down. Entered IMC approximately 8000 ft. Had difficulty keeping high rate of descent and was notified by bur approach several times to expedite descent. Bur asked if I was having a problem and I informed them of my trim and difficulty in pitch control. After intercepting inbound course, bur asked me my position. I informed them I was slightly to left of course (1/2 DOT on HSI). They replied I was to the right. I asked for a vector and was given 195 degrees. They asked if I wanted vectors for a VMC approach into vny and I declined. I tuned the #2 radio to smo VOR and used it for the remainder of the approach. Had the airport in sight about 1/2 the distance from culve intersection (2.4 DME) and the runway made an uneventful circle-to-land approach. Problem was traced to the worm gear on the trim actuator. It was found to have water and had been lubricated with improper grease. It was flushed with dow corning 33 grease. It is speculated that the water froze jamming the worm gear. I will inform my maintenance shop of the problem upon my return and also have the rudder and elevator fittings checked for proper grease. Callback conversation with reporter revealed the following information: the reporter stated the problem was caused by the wrong type elevator trim jackscrew lubricant which caused water to collect on the jackscrew acme nut, freeze, and prevent movement of the jackscrew. The reporter said when the mechanic opened up the jackscrew plate the water ran out. The reporter stated the correct grease was applied to the jackscrew and the elevator trim checked ok.
Original NASA ASRS Text
Title: A C340 IN CRUISE AT FL210 EXPERIENCED A FROZEN ELEVATOR TRIM CTL CAUSED BY THE INCORRECT JACKSCREW LUBRICANT.
Narrative: FLT FROM O48 TO SMO, ALT FL210. RTE O48-ENI-DIRECT AVENAL-FERNANDO 5 ARR SMO. PROB: AFTER LEVELING AT FL210, NOTED ELEVATOR TRIM WAS FROZEN. PULLED ELEVATOR TRIM CIRCUIT BREAKER -- NO EFFECT. IT WAS NECESSARY TO FLY WITH MODERATE FORWARD PRESSURE ON YOKE. UNTIL I ADJUSTED TO THIS, ALT VARIED +/-200 FT. APPROX 50 NM FROM FILMORE, WAS INSTRUCTED TO CROSS 10 NM NW OF FILMORE AT 11000 FT. I NOTIFIED CTR (ZLA) FEW MINS LATER OF AMOUNT OF FORWARD PRESSURE NEEDED AND NOSE WAS BOBBING UP AND DOWN. ENTERED IMC APPROX 8000 FT. HAD DIFFICULTY KEEPING HIGH RATE OF DSCNT AND WAS NOTIFIED BY BUR APCH SEVERAL TIMES TO EXPEDITE DSCNT. BUR ASKED IF I WAS HAVING A PROB AND I INFORMED THEM OF MY TRIM AND DIFFICULTY IN PITCH CTL. AFTER INTERCEPTING INBOUND COURSE, BUR ASKED ME MY POS. I INFORMED THEM I WAS SLIGHTLY TO L OF COURSE (1/2 DOT ON HSI). THEY REPLIED I WAS TO THE R. I ASKED FOR A VECTOR AND WAS GIVEN 195 DEGS. THEY ASKED IF I WANTED VECTORS FOR A VMC APCH INTO VNY AND I DECLINED. I TUNED THE #2 RADIO TO SMO VOR AND USED IT FOR THE REMAINDER OF THE APCH. HAD THE ARPT IN SIGHT ABOUT 1/2 THE DISTANCE FROM CULVE INTXN (2.4 DME) AND THE RWY MADE AN UNEVENTFUL CIRCLE-TO-LAND APCH. PROB WAS TRACED TO THE WORM GEAR ON THE TRIM ACTUATOR. IT WAS FOUND TO HAVE WATER AND HAD BEEN LUBRICATED WITH IMPROPER GREASE. IT WAS FLUSHED WITH DOW CORNING 33 GREASE. IT IS SPECULATED THAT THE WATER FROZE JAMMING THE WORM GEAR. I WILL INFORM MY MAINT SHOP OF THE PROB UPON MY RETURN AND ALSO HAVE THE RUDDER AND ELEVATOR FITTINGS CHKED FOR PROPER GREASE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE PROB WAS CAUSED BY THE WRONG TYPE ELEVATOR TRIM JACKSCREW LUBRICANT WHICH CAUSED WATER TO COLLECT ON THE JACKSCREW ACME NUT, FREEZE, AND PREVENT MOVEMENT OF THE JACKSCREW. THE RPTR SAID WHEN THE MECH OPENED UP THE JACKSCREW PLATE THE WATER RAN OUT. THE RPTR STATED THE CORRECT GREASE WAS APPLIED TO THE JACKSCREW AND THE ELEVATOR TRIM CHKED OK.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.