Federal Department of the Environment, Transport, Energy and Communications DETEC

Federal Office of Civil Aviation FOCA Safety Division

- Aircraft

Lufttü chtigkeitsanweisung (LTA) Consigne de Navigabilité (CN) Direttive sulla Navigabilità (DN) Airworthiness Directive (AD) FOCA AD 

## HB

- 20 14

- 001R1

Inkraftsetzung Mise en vigueur Entrata in vigore Effective Date 0 5 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 giuridic a: 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 D ate: 22 October 2014

ATA Chapter : ATA 51

– Standard Practices and Structures

Su bject: Standard Practices and Structures

– Aircraft Structure

– Identific a tion of Material Specification, Inspection

Su persedure / R e vi sed 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 prompte d 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 al umi n ium alloy AA2024

- T351 which is susceptible to Stress Corrosion Cracking (SCC ). Later in production, the material specification was changed to al u minium 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.

Suc h 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 P I LATUS PC

- 7 Servic e Bulletin (SB) No. 51

- 001 and FOCA Switzerland issued AD HB

- 2014

- 001 to require a one

- time check to identify the mat erial specification and inspect the affected areas of the ai r frame that are made of aluminium alloy AA2024

- T351. Any structural parts of th e aircraft structure found to be cracked must be reported to Pil a tus prior to further flight.

In the meantime Pilatus Aircraft Ltd. issued PILATUS PC

- 7 S B No. 51

- 001 Revision 1 to correct paragraphs (§) 1.C.(3 ) and § 1.D. to u pdate Part Number (P/N) refe rences of the AA2024

- T351 mat e rial and to add a clarification that an inspection can be carried out if an elevator ce nter co n trol

- rod P/N 116.35.07.345 is installed . It also clarifies which center tank su p port bracket is covered by SB 51

- 001.Lufttüchtigkeitsanweisung (LTA) Consigne de Navigabilité (CN) Direttive sulla Navigabilità (DN) Airwo rthiness Directive (AD) FOCA AD 

## HB

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- 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 de s 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 rea sons described above, this A D 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 paragraph s and clar i fies the information which center tank su p port bracket is affected.

Required A c tion(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) P erform 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 P I LATUS 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 e levator 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 th e inspection for cracks on this type of control

- rods is diff icult. 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 i n stalled, these type of control rods will be inspected.

(4) Pa rts (Items 1, 2, 4, 5 and 10 as listed in § 1.A.(2) of PIL A TUS 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 th e 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 P i latus.

NOTE: Repetitive mandatory in spections 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. Public a tion(s): PILATUS PC

- 7 Service Bu lletin No. 51

- 001 Revision 1

.
The use of later approved revisions of this document is ac ceptable for compliance with the r e quirements of this AD.

For further inform a tion

co n tact: The applicable manufacturer’s documentation may be obtained directly from:Lufttüchtigkeitsanweisung (LTA) Consigne de Navigabilité (CN) Direttive sulla Navigabilità (DN) Airwo rthiness Directive (AD) FOCA AD 

## HB

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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 de s 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 Productio n (STEH) CH

- 3003 Bern, Switzerland

Fax: +41 (0) 31 322 59 18 E

- mail: airdir@bazl.admin.ch