Airworthiness Directives

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81-12-06 R1 BENDIX: Amendment 39-4249. Applies to Bendix Engine Products Division D-3000 and D-3200 (Blue) series magnetos identified as follows, unless previously identified by the letter "X", on the upper left area of magneto data plate:

a. D-3000 series (see models specified under "MAGNETO IDENTIFICATION") pressurized (dark blue) magnetos with serial numbers below 1423, installed on AVCO Lycoming TIO, LTIO-540-J2BD engines.

MAGNETO IDENTIFICATION
MODEL	PART NO.
D6LN-3200	10-682910-13
D6RN-3200	10-682910-18

These magnetos are installed on but not limited to the following aircraft engines or aircraft engine/aircraft combinations:

AVCO LYCOMING ENGINES	AIRCRAFT INSTALLATIONS
TIO-540-J2BD	Piper PA-31-350;
LTIO-540-J2BD	STC SA1151SO and SA970SO Colemill conversion of Piper PA-31, PA-31-325 and PA-31-350; STC SA980NW Machen Industries conversion of Piper Aerostar 600 STC SA762NW Machen Industries conversion of Beechcraft Bonanza B35 and A36 series.

To detect loose distributor gear rotating electrodes on magnetos having 100 hours or more in service since new or overhaul, accomplish paragraph c, before further flight, unless previously accomplished, and every 50 hours in service thereafter until the gears are replaced with laser welded gear assemblies identified by the presence of the letter "Z" or the letters "XO" on the retaining ring end of the gear axle.

b. All D-3000 and D-3200 series (blue) magnetos with serial numbers 100 through 1968 not covered by paragraph a, unless previously accomplished.

To detect loose distributor gear rotating electrodes on magnetos having 100 hours or more in service since new or overhaul, accomplish paragraph c, before the expiration of 50 hours in service since new or overhaul after the effective date of this AD unless previously accomplished and every 50 hours in service thereafter until the gears are replaced with laser welded gear assemblies identified by the presence of the letter "Z" or the letters "XO" on the retaining ring end of the gear axle or the letter "L", stamped on the distributor gear electrode.

c. 1. Remove the distributor block from the magneto and the gears from the block.

2. (A). Inspect distributor gears and block for the presence of bronze colored particles and for indications of metal to metal contact of electrodes.

(B). Inspect rotating electrode for looseness by holding the gear in one hand while attempting to move the distributor gear electrode relative to the axle, clock-wise and vertically. Any looseness of the rotating electrode is reason for rejection of distributor gear.

3. If the distributor block is contaminated with brass filings or bronze colored dust, inspect the engine as follows:

(A). Observe engine pistons through spark plug hole for evidence of burning.

(B). Check valve dry tappet clearance per engine manufacturer's instructions.

If piston damage or lower than specified dry tappet clearance is present, the engine must be inspected, in accordance with the engine manufacturer's instructions, for continued airworthiness.

4. Reinstall serviceable distributor gears into a clean serviceable distributor block. Reassemble the magneto and check timing as appropriate.

5. (A). Make an engine log entry of compliance, including magneto serial number.

(B). When the laser beam welded distributor gear has been installed in a D-3000 or D-3200 series magneto, identify that magneto by metal stamping the letter "X", on the upper left area of magneto data plate and make the appropriate log entry.

Equivalent inspections and procedures must be approved by the Chief of the Engineering and Manufacturing Branch, AEA-210, Federal Aviation Administration (FAA) Eastern Region. As permitted by FAR 21.197, aircraft may be flown to a base where maintenance required by this AD can be accomplished.

(Bendix Service Bulletins 618 and 619 pertain to paragraphs a and b respectively.)

This Airworthiness Directive is effective November 12, 1981, and paragraph a. was effective upon receipt for all recipients of airmail letter dated June 5, 1981, which covered that subject.



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