AD/Cessna 170/79 Crew Seat Back Cylinder Lock Modification (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes

AD/CESSNA 170/79 Crew Seat Back Cylinder Lock Modification 5/2007 DM

Applicability:

Cessna 172R (Serial Numbers 17280001 through 17281262) and Cessna 172S (Serial Numbers 172S8001 through 172S9994).

Requirement:

1)    Aeroplanes that do not have Modification Kit MK172-25-10A or Modification Kit MK172-25-10B installed, for each crew seat (pilot and copilot), install Modification Kit MK172-25-10C or fabricate and install a steel lock rod/bar. Follow Cessna Single Engine Service Bulletin SB04-25-01, Revision 4, dated December 26, 2006, for installing Modification Kit MK172-25-l0C, or, follow Cessna Single Engine Service Bulletin SB04-25-02, Revision 1, dated October 17, 2005, or Revision 2, dated June 5, 2006, for fabricating and installing a steel lock rod/bar.

2)    Aeroplanes that have Modification Kit MK172-25-10A or Modification Kit MK172-25-10B installed:

(i)    For each crew seat (pilot and co-pilot), perform an installation inspection in accordance with Cessna Single Engine Service Bulletin SB04-25-01, Revision 4, dated 26 December 2006.

(ii)   If you do not find any discrepancies during the inspection required in paragraph (2)(i) of this AD, make a log book entry showing compliance with this AD and no further action is required.

(iii)   If you find discrepancies during the inspection required in paragraph (2)(i) of this AD, make all necessary corrective actions in accordance with Cessna Single Engine Service Bulletin SB04-25-01, Revision 4, dated 26 December 2006.

Note:  FAA AD 2007-05-10 Amdt 39-14971 and Cessna Service Bulletins SB04-25-01 and SB04-25-02 refer.

Compliance:

1)    For aeroplanes over 1,000 hours time-in-service (TIS) on the effective date of this AD, perform the action within the next 4 months after the effective date of this AD; or

For aeroplanes from 501 to 1,000 hours TIS on the effective date of this AD, perform the action within the next 8 months after the effective date of this AD; or

For aeroplanes from 0 to 500 hours TIS on the effective date of this AD, perform the action within the next 12 months after the effective date of this AD.

2)    For aeroplanes meeting Requirement 2:

(i)    Within the next 30 days after the effective date of this AD.

(ii)   Before further flight after the inspection required in paragraph 2(i) of this AD.

(iii)   Before further flight after the inspection required in paragraph 2(i) of this AD.

This Airworthiness Directive becomes effective on 11 April 2007.

Background:

This AD results from reports of the crew seat back cylinder lock assembly failing at the aft end area and other cylinder lock assemblies found cracked.  The actions specified in this AD are intended to prevent the crew seat cylinder lock assembly from bending, cracking, or failing.  This failure could cause uncontrolled movement of the seat back, resulting in possible backward collapse during flight.  Backward collapse of either crew seat back could result in an abrupt pitch-up if the affected crew member continues to hold on to the control yoke during this failure and could cause difficulty in exiting the airplane from an aft passenger seat after landing.

David Villiers
Delegate of the Civil Aviation Safety Authority

9 March 2007