EASA AD No.: 2009-0220 

EASA Form 110 Page 1/2

EASA AIRWORTHINESS DIRECTIVE 

AD No.: 2009-0220 

Date: 14 October 2009 

Note: This Airworthiness Directive (AD) is issued by EASA, acting in accordance with Regulation 

(EC) No 216/2008 on behalf of the European Community, its Member States and of the 

European third countries that participate in the activities of EASA under Article 66 of that 

Regulation.

This AD is issued in accordance with EC 1702/2003, Part 21A.3B. In accordance with EC 2042/2003 Annex I, Part M.A.301, the 

continuing airworthiness of an aircraft shall be ensured by accomplishing any applicable ADs. Consequently, no person may operate 

an aircraft to which an AD applies, except in accordance with the requirements of that AD, unless otherwise specified by the Agency 

[EC 2042/2003 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/2008, Article 14(4) exemption]. 

Type Approval Holder’s Name : 

Fokker Services B.V.

Type/Model designation(s) : 

F28 Mark 0070 and Mark 0100 aeroplanes 

TCDS Number : EASA.A.037 

Foreign AD : Not applicable 

Supersedure : None 

ATA 32 Landing Gear – Parking Brake Shut-off Valve (PBSOV) – 

Replacement 

Manufacturer(s): Fokker Aircraft B.V. 

Applicability: F28 Mark 0070 and Mark 0100 aeroplanes, all serial numbers. 

Reason: 

When preparing for landing, the flight crew of a F28 Mark 0100 (Fokker 100) 

aeroplane observed a main landing gear (MLG) unsafe indication after landing 

gear down selection. The approach was aborted and the landing gear unsafe 

procedure was accomplished. As this did not produce the desired effect, a low 

pass was performed and the control tower confirmed that the right (RH) MLG 

was partly extended and the left (LH) MLG door was open but without the MLG 

being extended. Eventually the aeroplane landed with partly extended landing 

gear, without resulting in serious injuries to the occupants. 

Subsequent investigation revealed that the cause of the MLG extension 

problem was the (partially) blocked hydraulic return line from the MLG selector 

valve by pieces of hard plastic. These were identified as parts of the poppet 

seat of PBSOV Part Number (P/N) 70379. The PBSOV installed on the incident 

aeroplane was a modified version of P/N 70379, identified by suffix “A” behind 

the serial number on the identification plate. This modification was introduced 

by Eaton, the valve manufacturer, with Eaton Service Bulletin (SB) 70379-32-01 

and includes replacement of the original poppet with clamped hard plastic seat 

by an improved poppet assembly with screwed-on seat. When the affected 

valve was opened, it was confirmed that it contained the improved poppet 

assembly. The poppet seat fragments found in the return system therefore 

originated from a previously installed (pre SB 70379-32-01) P/N 70379 PBSOV 

and must have been present in the return/pressure line prior to installation of 
EASA AD No.: 2009-0220 

EASA Form 110 Page 2/2

the modified PBSOV. 

This condition, if not detected and corrected, could lead to further events where 

the MLG fails to extend, possibly resulting in loss of control of the aeroplane 

during landing. 

For the reasons described above, this AD requires the inspection of the 

associated hydraulic lines, irrespective what type PBSOV is installed, removal 

of contamination in the system, if any, and replacement of each unmodified 

PBSOV with a modified unit. This AD also prohibits, after installation of a 

modified PBSOV on an aeroplane, re-installation of an unmodified PBSOV on 

that aeroplane. 

Effective Date: 28 October 2009 

Required Action(s) 

and Compliance 

Time(s): 

Required as indicated, unless accomplished previously: 

(1) Within 30 days after the effective date of this AD, inspect the hydraulic 

lines associated with the PBSOV for the presence of pieces of material 

from the unmodified P/N 70379 PBSOV poppet seat and, depending on 

findings, accomplish the necessary corrective actions before further flight, 

in accordance with Part 1 of the Accomplishment Instructions of Fokker 

Services SBF100-32-159. 

(2) Within 18 months after the effective date of this AD, re-inspect the 

hydraulic lines as required by paragraph (1) of this AD and modify the 

aeroplane by replacing the unmodified P/N 70379 PBSOV with a modified 

P/N 70379 PBSOV (identified by suffix “A” behind the serial number on the 

identification plate) in accordance with Part 2 of the Accomplishment 

Instructions of Fokker Services SBF100-32-159. 

(3) After modification of an aeroplane as required by paragraph (2) of this AD, 

do not install a P/N 70379 PBSOV on that aeroplane, unless the PBSOV 

has been modified in accordance with Eaton SB 70379-32-01 (identified 

with suffix “A” behind the serial number on the identification plate). 

Ref. Publications: 

Fokker Services SBF100-32-159 dated 06 October 2009. 

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

compliance with the requirements of this AD. 

Eaton Service Bulletin 70379-32-01. 

Remarks :

1. If requested and appropriately substantiated, EASA can approve 

Alternative Methods of Compliance for this AD. 

2. The required actions and the risk allowance have granted the issuance of a 

Final AD with Request for Comments, postponing the public consultation 

process after publication. 

3. Inquiries regarding this AD should be referred to the Airworthiness 

Directives, Safety Management & Research Section, Certification 

Directorate, EASA. E-mail ADs@easa.europa.eu 

4. For any question concerning the technical content of the requirements in 

this AD, please contact: 

Fokker Services B.V., Technical Services Dept., P.O.Box 231, 

2150 AE Nieuw-Vennep, The Netherlands; 

telephone (31) 252-627-350; facsimile (31) 252-627-211; 

e-mail: technicalservices.fokkerservices@stork.com 

The referenced publication can be downloaded from 

www.myfokkerfleet.com