# AD 81-12-51: Rudder Close Tolerance Bolt

- Type: Airworthiness directive
- Status: Current
- Products: Flug- und Fahrzeugwerke Diamant 16.5 and HBV Diamant
- Effective: October 22, 1981
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Glider
- Amendment: 39-4239
- Registered aircraft: 3 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/EDF9A72690CFA7C886256A4E00495471.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/81-12-51

## The airworthiness directive

81-12-51 FLUG UND FAHRZEUGWERKE AG: Amendment 39-4239. Applies to AG Model Diamant HBV and 16.5 gliders, certificated in all categories.

Compliance required as indicated, unless already accomplished.

To prevent loss of the rudder lower close tolerance bolt, which could result in loss of the rudder, accomplish the following:

  (a) Before further flight, unless already accomplished within the last 25 flight hours, and thereafter at intervals not to exceed 25 flight hours until replacement per paragraph (b) is accomplished, inspect the rudder close tolerance bolt for tightness in accordance with Flug Und Fahrzeugwerke AG Service Bulletin Number 10, dated April 1981, or in accordance with applicable criteria of FAA Advisory Circular 43.13-1A. If the bolt is loose (free to rotate), before further flight, replace the bolt in accordance with the above noted Service Bulletin, or an FAA- approved equivalent.

  (b) Unless already accomplished, prior to January 1, 1982, replace the rudder close tolerance bolt in accordance with Flug Und Fahrzeugwerke AG Service Bulletin Number 10, dated April 1981, or an FAA-approved equivalent, as follows:

  (1) Remove rudder as follows:

    (i) Push rudder to the right deflection limit so that the bolt is visible through the opening on the left side of the rudder.

    (ii) Remove connecting bolt at the end of the push rod.

    (iii) Remove close tolerance bolt.

    (iv) Remove rudder from the bearing block by pulling the rudder backwards. As soon as the rudder is off the bearing block, pull the rudder downwards to remove it from the upper bearing.

  (2) Modification procedure:

    (i) On the lower bearing block, remove both rivets from the anchor nut. Then rivet bracket and sheet together again (without anchor nut).

    (ii) Mount rudder in reverse order to Item 1.

    (iii) Check deflections according to the flight manual, Item 5.2. (plus or minus 30 degrees, +3 degrees, -0 degrees).(iv) Check rudder and elevator controls for free movement.

  (3) Material:

Materials Part Number 1 connecting bolt D1.206-0303 1 spacer R20002 AN 960-C10L 2 castle nuts M6 VSM 13780 2 cotter pins 1.6 x 16 VSM 12760 1 close tolerance bolt D1.201-1228.1 2 rivets MS 20470-AD2-10

  (c) For the purpose of compliance with this AD, an equivalent procedure may be approved by the Chief of the FAA Engineering and Manufacturing Branch of any FAA region.

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Flug Und Fahrzeugwerke AG, CH-9422 Staad SG, Switzerland. These documents may be examined at FAA Headquarters, Room 916, 800 Independence Avenue, SW., Washington, D.C. 20591.

This amendment becomes effective October 22, 1981, as to all persons except those persons to whom it was made immediately effective by telegraphic AD T81-12-51, issued June 10, 1981, which contained this amendment.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS G13EU](https://openairdocs.org/tcds/G13EU): Flug- und Fahrzeugwerke Ag; names 2 of 2 models: HBV Diamant, Diamant 16.5

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 3 (3 by airframe model, 0 by engine model)
- Makers: Flug & Fahrzeugwerke 3

Models with the most aircraft:

- [Flug & Fahrzeugwerke DIAMANT 16.5](https://openairdocs.org/model/flug-fahrzeugwerke-diamant-16-5): 3 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/81-12-51/models.md
Every aircraft: https://openairdocs.org/ad/81-12-51/aircraft.md

## Related documents

- [AC 43.13-1B CHG 1 Ed Update](https://openairdocs.org/ac/43.13-1): Acceptable Methods, Techniques, and Practices—Aircraft Inspection and Repair. Cited as AC 43.13-1A in the AD's requirements

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