Commonwealth legislation

AD/F27/38 - ADF Sense Antenna - Modification

RepealedCTH

This Act has been repealed and is no longer in force. It is retained for historical reference.

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

2/10 complexity

This Airworthiness Directive requires owners and operators of Fokker F27 aircraft fitted with Bendix DFA-70A ADF equipment to modify the Automatic Direction Finder (ADF) sense antenna to meet specific technical standards.

What it does: Mandates modifications to navigation equipment to ensure accurate directional readings and flight safety.

Technical requirements: The modified antenna must achieve:

Effective height: At least 0.25 metres
Sensitivity product value: Between 12 and 25 micro-microfarads-meters (a measurement of electrical performance)
Total capacity: 270 micro-microfarads, plus or minus 10%, measured at the receiver input terminals
Tilt angle: Between -20 and +10 degrees

Who it affects: Operators and maintenance organisations responsible for Fokker F27 aircraft equipped with the specified Bendix navigation systems.

Why it matters: These specifications ensure the ADF equipment—which helps pilots determine their bearing relative to ground-based radio beacons—operates reliably and accurately, directly impacting aviation safety.

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AD/F27/38 - ADF Sense Antenna - Modification

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COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source Fokker F27 Series Aeroplanes

AD/F27/38 ADF Sense Antenna - Modification 12/67

Applicability: All models fitted with Bendix type DFA-70A ADF equipment.

Requirement: Modify the sense antenna to achieve the following minimum performance characteristics:-

(a) Effective Height : Not less than 0.25 metres.

(b) Sensitivity Product Value : Between the limits of 12 and 25 micro-microfarads- meters.

(c) Total capacity of antenna and transmission line presented to receiver input terminals : 270 micro-microfarads + 10%.DE

(d) Tilt Angle : between the limits of -20º and +10º.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.