AIRWORTHINESS BULLETIN AWB 57-009 Issue : 2 Piper PA-31 Series Aircraft: Wing Leading Edge Stall Strip Configuration

Full document text

AIRWORTHINESS BULLETIN AWB 57-009 Issue : 2 Piper PA-31 Series Aircraft: Wing Leading Edge Stall Strip Configuration Date : 10 September 2010 1. Applicability All Piper PA-31 Series Navajo and Chieftain aircraft. 2. Purpose This AWB has been raised to clarify the wing leading edge stall strip (or flow strip) configuration requirements for the PA-31 Series. Issue 2 has been published in response to additional information from Piper and the changes are indicated by a vertical bar in the Appendix. 3. Background Prior to May 1969 Piper PA-31 Series aeroplanes did not have wing leading edge stall strips installed at manufacture. It was subsequently found that the installation of wing leading edge stall strips markedly improved the aircraft’s low speed flight handling characteristics. Piper immediately commenced installing leading edge stall strips at the factory and issued Piper SB No. 294 to ensure wing leading edge stall strips were installed on PA31 Series aircraft with serial numbers up to 31-445. SB No. 294 was mandated by FAA AD 69-11-05. It has come to CASA’s attention that some PA-31 aircraft have no leading edge stall strips, and that some stall strips are not of the correct part number, correct configuration or in the correct location. Unless wing leading edge stall strips of the correct dimensions are installed in the correct configuration, including the correct position on the leading edge, the aircraft does not conform to the Type Design. Stall strips may have been inadvertently omitted when the de-ice boots were removed or when the wings were re-painted. Information found in the Illustrated Parts Catalogue (IPC) suggests that stall strip configuration is dependant on wing locker installation. In order to verify the correct stall strip configuration, Piper has researched the original wing leading edge de-ice drawings along with the wing and wing locker installation and component drawings. It was found that it is the airframe model and serial number ranges, not wing locker installation, that determines the correct stall strip configuration. As a result of its investigations, Piper advises that it intends to correct the references in the PA31 Series IPC, which links wing locker configuration to stall strip installation. Piper has courteously provided CASA with the results of its research in advance of the proposed revision to the IPC (Refer Appendix). It should be noted that this information only provides clarification with regard to the general configuration and number of stall strips required for the various PA-31 serial numbers. The applicable Piper IPC should be consulted to determine the correct part number of each stall strip. The precise location of each stall strip on the wing leading edge is critical. If the stall strips must be removed during maintenance, the Page 1 of 3 AIRWORTHINESS BULLETIN AWB 57-009 Issue : 2 Piper PA-31 Series Aircraft: Wing Leading Edge Stall Strip Configuration Date : 10 September 2010 instructions provided in the Piper Service Manuals should be followed and the position of the stall strips should be carefully marked before removal. However, if the stall strips have been removed but their positions were not marked before removal, a Piper Dealer should be contacted for assistance with identifying the precise location for each stall strip. 4. Recommendation Operators of PA-31 Series aircraft are advised to urgently review the installation of the wing leading edge stall strips and ensure they conform to Type Design. 5. Enquiries Enquiries with regard to the content of this Airworthiness Bulletin should be made via the direct link e-mail address: AirworthinessBulletin@casa.gov.au Or in writing, to: Airworthiness Engineering Branch Civil Aviation Safety Authority GPO Box 2005, Canberra, ACT, 2601 Page 2 of 3 AIRWORTHINESS BULLETIN AWB 57-009 Issue : 2 Piper PA-31 Series Aircraft: Wing Leading Edge Stall Strip Configuration Date : 10 September 2010 Note: Reference to, or inclusion of manufacturers data in an AWB is not subject to revision. Appendix Piper PA 31 — Series Wing Leading Edge Stall Strip Configuration. PA 31 Model Serial Number Range De-Ice Boots Installed? Port Wing (in board) (LH) Port Wing (out board) (LH) Stb’d. Wing (inboard) Stb’d. Wing (outboard) (RH) (RH) Stall strip installation configuration 31-300 ALL No One None One One 31-5 TO Yes One None One One 31-7612076 31-7612077 to Yes One None One One 31-7912124 31-8012001 &up. Yes One None One One 31-310 ALL No One None One One 31-5 to Yes One None One One 31-7612076 31-7612077 to Yes One None One One 31-7912076 31-8012001 & up Yes One None One One 31-325 ALL No One None One None 31-5 to 31-7612076 Yes One None One None 31-7612077 to 31-7912076 Yes One None One None 31-8012001 & up Yes One None One None Serial Number Range De-ice Stbd. Wing (RH) approx. centre Wing Sta. 160 Port Wing (LH) approx. centre Wing Sta. 160 Boots Installed? Stall strip installation configuration 31-350 All No One One 31-5001 to Yes One One 31-7652123 31-7652124 to 31-7952250 Yes One One 31-8052001 & up Yes One One Page 3 of 3