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-2014-001R1

Inkraftsetzung

Mise en vigueur

Entrata in vigore

Effective Date

05 November 2014 Pilatus – PC-7

FOCA TC/TCDS No: F 56-20

1/3

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: 22 October 2014

ATA Chapter: ATA 51 – Standard Practices and Structures

Subject: Standard Practices and Structures – Aircraft Structure –

Identification of Material Specification, Inspection

Supersedure / Revised

AD(s):

HB-2014-001

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 possibility of 

cracks in some critical parts. It is possible that stress corrosion cracks 

may occur on various parts of the aircraft structure initially made of aluminium alloy AA2024-T351 which is susceptible to Stress Corrosion 

Cracking (SCC). 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 affected structural parts are not 

always changed when the new material was introduced.

Such a condition, if left uncorrected, could lead to failure of critical parts 

on the aircraft structure and will prejudice the structural integrity of the 

aircraft.

To address this potential unsafe condition Pilatus Aircraft Ltd. issued 

PILATUS PC-7 Service Bulletin (SB) No. 51-001 and FOCA Switzerland 

issued AD HB-2014-001 to require a one-time check to identify the material specification and inspect the affected areas of the airframe that are 

made of aluminium alloy AA2024-T351. Any structural parts of the aircraft 

structure found to be cracked must be reported to Pilatus prior to further 

flight.

In the meantime Pilatus Aircraft Ltd. issued PILATUS PC-7 SB 

No. 51-001 Revision 1 to correct paragraphs (§) 1.C.(3) and § 1.D. to update Part Number (P/N) references of the AA2024-T351 material and to 

add a clarification that an inspection can be carried out if an elevator center control-rod P/N 116.35.07.345 is installed. It also clarifies which center 

tank support bracket is covered by SB 51-001.
Lufttüchtigkeitsanweisung (LTA)

Consigne de Navigabilité (CN)

Direttive sulla Navigabilità (DN)

Airworthiness Directive (AD)

FOCA AD

HB-2014-001R1

2/3

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)

For the reasons described above, this AD retains the requirements of 

FOCA Switzerland AD HB-2014-001, which is revised and clarifies that an 

inspection of the elevator center control-rod can be carried out if 

P/N 116.35.07.345 is installed and corrects some paragraphs and clarifies 

the information which center tank support bracket is affected.

Required Action(s) 

and Compliance 

Time(s):

Required as indicated below, unless already accomplished, within the next 

365 days after the effective date of this AD:

(1) Perform a one time conductivity test of items 6 thru 9 and 11 thru 13 

(both on aircraft and those held in stores) as listed in § 1.A.(2) of 

PILATUS PC-7 SB No. 51-001 Revision 1, to check the material of the 

parts.

(2) If the parts are made of aluminium alloy AA2124-T851, make an entry 

in the aircraft logbook as required by § 3.D.(3) of PILATUS PC-7 SB 

No. 51-001 Revision 1.

(3) Replace elevator center control-rods with P/N 116.35.07.271 (Item 3

as listed in § 1.A.(2) of PILATUS PC-7 SB No. 51-001 Revision 1), 

because the inspection for cracks on this type of control-rods is difficult. If elevator center control-rods P/N 116.35.07.345 (Item 3 as listed 

in § 1.A.(2) of PILATUS PC-7 SB No. 51-001 Revision 1), are 

installed, these type of control rods will be inspected.

(4) Parts (Items 1, 2, 4, 5 and 10 as listed in § 1.A.(2) of PILATUS PC-7 

SB No. 51-001 Revision 1) are made of aluminium alloy 

AA2024-T351. Therefore:

• Do a one time inspection for cracks of Items 1, 2, 4 and 10

• Replace Item 5

(5) If the conductivity test shows the parts are made of aluminium alloy 

AA2024-T351:

a) For Items 7 thru 9 and 11 thru 13 as listed in § 1.A.(2) of 

PILATUS PC-7 SB No. 51-001 Revision 1, do a one time 

inspection for cracks. If cracks are found, contact Pilatus.

NOTE: Repetitive mandatory inspections will be added to 

Chapter 5 of the Aircraft Maintenance Manual (AMM). The 

inspections will give instructions on how to examine the parts 

for cracks. The inspections will only be applicable to parts 

made from AA2024-T351.

b) For Item 6 as listed in § 1.A.(2) of PILATUS PC-7 SB 

No. 51-001 Revision 1, replace the part with a part made of 

aluminium alloy AA2124-T851.

Ref. Publication(s): PILATUS PC-7 Service Bulletin No. 51-001 Revision 1.

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:
Lufttüchtigkeitsanweisung (LTA)

Consigne de Navigabilité (CN)

Direttive sulla Navigabilità (DN)

Airworthiness Directive (AD)

FOCA AD

HB-2014-001R1

3/3

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)

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