# AD 73-20-05: Float To Fuselage Bolts

- Type: Airworthiness directive
- Status: Current
- Products: Viking Air DHC-6-1, DHC-6-100, DHC-6-200 and DHC-6-300
- Effective: October 3, 1973
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1725
- Registered aircraft: 88 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/ED095FCF241777F086256A380048B6ED.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/73-20-05

## The airworthiness directive

73-20-05 de HAVILLAND: Model DHC-6. Amdt. 39-1725. Applies to de Havilland Model DHC-6 Twin Otter Floatplanes, all Series, certificated in all categories, equipped with Canadian Aircraft Products Model 12000A or 12000B Floats installed prior to Float Serial No. 71.

1. Compliance is required within the next ten hours in service from the effective date of this Airworthiness Directive, unless already accomplished.

To prevent loosening and subsequent pullout failure of certain float to fuselage bolts, comply with accomplishment instruction of de Havilland Service Bulletin 6/296, Revision A, dated May 11, 1973, or an equivalent alteration approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.

This amendment is effective October 3, 1973.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A9EA](https://openairdocs.org/tcds/A9EA): De Havilland Aircraft of Canada Limited; names 4 of 5 models: DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300

## 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: 88 (88 by airframe model, 0 by engine model)
- Makers: Dehavilland 84, Dehavilland Acft Of Canada 4

Models with the most aircraft:

- [Dehavilland DHC-6-300](https://openairdocs.org/model/dehavilland-dhc-6-300): 59 aircraft (airframe model)
- [Dehavilland DHC-6-200](https://openairdocs.org/model/dehavilland-dhc-6-200): 19 aircraft (airframe model)
- [Dehavilland DHC-6-100](https://openairdocs.org/model/dehavilland-dhc-6-100): 6 aircraft (airframe model)
- [Dehavilland Acft Of Canada DHC 6-300](https://openairdocs.org/model/dehavilland-acft-of-canada-dhc-6-300): 4 aircraft (airframe model)

All 4 models: https://openairdocs.org/ad/73-20-05/models.md
Every aircraft: https://openairdocs.org/ad/73-20-05/aircraft.md

Its text cites no advisory circulars or STCs.

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