Federal Department of the Environment, Transport, Energy and 

Communications DETEC

Federal Office of Civil Aviation FOCA

Safety Division - Aircraft

Lufttüchtigkeitsanweisung (LTA)

Consigne de Navigabilité (CN)

Direttive sulla Navigabilità (DN)

Airworthiness Directive (AD)

FOCA AD

HB-2012-009

Inkraftsetzung

Mise en vigueur

Entrata in vigore

Effective Date

03 January 2013 Pilatus – PC-7

FOCA TC/TCDS No: F 56-20

1/2

Rechtsgrundlage: Art. 26, 51 und 51A (Verordnung über die Lufttüchtigkeit von Luftfahrzeugen: SR 748.215.1)

Base juridique: Art. 26, 51 et 51A (Ordonnance sur la navigabilité des aéronefs: SR 748.215.1)

Base giuridica: Art. 26, 51 e 51A (Ordinanza concernente la navigabilità degli aeromobili: SR 748.215.1)

Legal base: Art. 26, 51 and 51A (Ordinance on the airworthiness of aircraft: SR 748.215.1)

Issue Date: 20 December 2012

ATA Chapter: ATA 53 – Fuselage

Subject: Fuselage / Engine Mount Fittings – Inspection

Supersedure / Revised

AD(s):

Not applicable

Type Certificate 

Holder’s Name:

Pilatus Aircraft Ltd.

Manufacturer(s): Pilatus Aircraft Ltd.

Applicability: Model PC-7 aircraft, Manufacturer Serial Numbers (MSN) 101 through 

MSN 618.

Reason: This Airworthiness Directive (AD) is prompted due to the discovery of

cracks in the engine mount fittings. The cracks are caused by stress corrosion. It is possible for stress corrosion cracks to occur on engine mount 

fittings initially made of aluminium alloy AA2024-T351. Later in production, 

the material specification was changed to aluminium alloy AA2124-T851 

to decrease the risk of stress corrosion. The Part Number (P/N) of the 

engine mount fittings remained the same.

Such a condition, if left uncorrected, could lead to failure of the engine 

mount fittings and possible failure of the engine attachment.

In order to correct and control the situation, this AD requires a one-time 

check to identify the material specification and inspect those affected engine mount fittings that are made of aluminium alloy AA2024-T351. Any 

engine mount fittings found to be cracked must be reported to Pilatus

prior to further flight.

Required Action(s) 

and Compliance 

Time(s):

Required as indicated below, unless already accomplished:

(1) Within the next 90 days after the effective date of this AD, perform a 

conductivity test to identify the material specification of the engine 

mount fittings (P/N 112.35.07.152) as required by paragraph (§) 3.B. 

of PILATUS PC-7 Service Bulletin No. 53-008.
Lufttüchtigkeitsanweisung (LTA)

Consigne de Navigabilité (CN)

Direttive sulla Navigabilità (DN)

Airworthiness Directive (AD)

FOCA AD

HB-2012-009

2/2

Rechtsgrundlage: Art. 26, 51 und 51A (Verordnung über die Lufttüchtigkeit von Luftfahrzeugen: SR 748.215.1)

Base juridique: Art. 26, 51 et 51A (Ordonnance sur la navigabilité des aéronefs: SR 748.215.1)

Base giuridica: Art. 26, 51 e 51A (Ordinanza concernente la navigabilità degli aeromobili: SR 748.215.1)

Legal base: Art. 26, 51 and 51A (Ordinance on the airworthiness of aircraft: SR 748.215.1)

(2) If during the conductivity test required by § (1) of this AD, engine 

mount fittings made of aluminium alloy AA2024-T351 are found, 

within the next 90 days after the effective date of this AD, perform

the inspection in accordance with (§) 3.C. of PILATUS PC-7 Service 

Bulletin No. 53-008.

Note 1: The Aircraft Maintenance Manual (AMM) will be updated to 

include repetitive inspections of all engine mount fittings made of 

aluminium alloy AA2024-T351.

(3) If during the inspection required by § (2) of this AD, cracks are found 

in the engine mount fittings, prior to further flight, contact Pilatus Customer Technical Support (MCC) for further instructions.

Ref. Publication(s): PILATUS PC-7 Service Bulletin No. 53-008, initial issue.

The use of later approved revisions of this document is acceptable for 

compliance with the requirements of this AD.

For further information 

contact:

The applicable manufacturer’s documentation may be obtained directly 

from:

PILATUS AIRCRAFT LTD.

Customer Technical Support (MCC)

P.O. Box 992

CH-6371 Stans, Switzerland

Tel.: +41 (0)41 619 67 74 Fax: +41 (0)41 619 67 73

E-mail: Techsupport@pilatus-aircraft.com

For further information contact:

FEDERAL OFFICE OF CIVIL AVIATION (FOCA)

Design and Production (STEH)

CH-3003 Bern, Switzerland

Fax: +41 (0) 31 322 59 18

E-mail: airdir@bazl.admin.ch