# Aircraft Industries Mandatory Bulletin L13/085a Copy: No revision named ("LET L13-085a mandatory bulletin"), 7 pages: PDF https://openairdocs.org/files/sha256/1f/21/1f2118a4540f1da666406b121f46002313de6871a144a60e707a978e3ce4f002; text https://openairdocs.org/service-documents/aircraft-industries/l13-085a/file/1f2118a4540f.md. Rights: © Aircraft Industries. Filed by the FAA in regulations.gov docket FAA-2016-4231; AD 2016-11-10 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. ## Details - Manufacturer: [Aircraft Industries](https://openairdocs.org/service-documents/aircraft-industries.md) - Type: Service bulletin (Mandatory Bulletin) - Number: L13/085a - Page: https://openairdocs.org/service-documents/aircraft-industries/l13-085a ## ADs that cite it (2) (OpenAirDocs) Newest first, with the revision each names, as OpenAirDocs read it from the AD's text. - [AD 2016-11-10](https://openairdocs.org/ad/2016-11-10.md), effective Jul 8, 2016: No revision named - [AD 2000-20-11](https://openairdocs.org/ad/2000-20-11.md), effective Nov 27, 2000: No revision named Also cited in [2 proposed ADs](https://openairdocs.org/service-documents/aircraft-industries/l13-085a/proposed.md). ## Text (7 pages) Rights: © Aircraft Industries. Filed by the FAA in regulations.gov docket FAA-2016-4231; AD 2016-11-10 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. This text is OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 (OCR) 11/2/2015 LET L13-085a mandatory bulletin MANDATORY BULLETIN No. L13/085a Concerning: L13, L13A sailplanes Reason: On the L 13 BLANIK sailplane S/N 027226, the tail- fuselage attachment fitting P/N A 102 021 N made of 424253.11 material has been damaged in service. The material of this component must be tested as instructed in this Bulletin. To be accomplished not later than: December 31, 1999 To be accomplished by: The operator Cost covered by: The operator Material availability: Validity: Upon the approval date Total number of sheets: ing. Pesak / Manufacturer Engineering data contained in this Bulletin is CAI Approved. Date: November 17, 1999 LET, a.s., Kunovice 686 04, Czech Republic L13/085a Sheet 1 of 5 ==== A. WORK PROCEDURE 1. Remove the oval cover located on the LH side of the fuselage, under the horizontal stabilizer. 2. Test the material of the attachment fitting P/N A 102 021 N as follows: a) Conductivity measurement by means of eddy currents: - Recommended measurement frequency: 60 kHz - Probe diameter: not exceeding 15 mm - Measuring contact point: lower milled surface of the component, between the rivets (see, Figs. 1 and 2). Permissible range of measured values: % IACS: 28.5 - 35.0 MS/m: 15.0 - 20. Note: The surface protective coating of the component need not be removed. b) Hardness measurement by means of a portable digital hardness tester. Measuring method: depending on the type of the hardness tester used, i.e. dynamic, ultrasonic, and/or by means of a manual probe. Measuring point: lower milled surface of the component. Measured value: not lower than 100 HB. http://home.nwi.net/~blanikam/ba/l13-085a.htm 1/7 ### Page 2 (OCR) 11/2/2015 LET L13-085a mandatory bulletin c) Any other measuring method must be approved by the sailplane manufacturer before it can be used. 3.1 If the values measured during the check are within the permissible limits specified above, make a record in the sailplane logbook (see section H of this Bulletin). The sailplane operation can be continued without any limitations. 3.2 If the values measured during the check are not within the permissible limits, the attachment fitting P/N A 102 021 N must be replaced before the sailplane operation can be continued. 4. If the attachment fitting P/N A 102 021 N is to be replaced, the operator shall place an order with the manufacturer, stating the sailplane Serial No., number of flight hours, registration mark, and number of its repairs and/or overhauls. 5. The manufacturer will send to the operator the material required for replacement, together with a bulletin providing the work procedure. 6. After the check, reinstall the inspection hole cover. L13/085a Sheet 2 of 5 ===== D. MATERIAL REQUIRED FOR MODIFICATION OF ONE SAILPLANE None. C. ILLUSTRATIONS Figs 1 and 2. D. DOCUMENTATION REQUIRED None. E. TOOLS REQUIRED Material hardness testing equipment: Eddy current conductivity meter Hardness tester F. SPARE PARTS IN OPERATION The spare parts in stock, if any, must be tested as instructed in Section A, item 2 of this Bulletin. G. SAILPLANE MASS Not affected. H. RECORD IN LOGBOOK AFTER BULLETIN IMPLEMENTATION L13/085a Attachment fitting P/N A 102 021 N material hardness tested. Measured values: http://home.nwi.net/~blanikam/ba/l13-085a.htm 217 ### Page 3 (OCR) 11/2/2015 LET L13-085a mandatory bulletin Sailplane cleared for operation. Date: Carried out by: (legible signature of authorized engineer) I. ACCOMPANYING DOCUMENTATION Not affected. Contact Address: LET, a.S. Product Support Dept. 686 04 Kunovice 1177 Czech Republic tel 0632/55 44 96; fax 0632/56 41 13 E-mail: ots@let.cz L13/085a Sheet 3 of 5 ===== Sheets 4 and 5: Fig. 1 and Fig. 2 http://home.nwi.net/~blanikam/ba/113-085a.htm ### Page 4 (OCR) 11/2/2015 LET L13-085a mandatory bulletin Measurinq contant point L13/085a Fig 1. and 2. ' inspection cover Fuselage palahead N. 14 Fig. 1 Fig. 2 Fuselage bulkhead N. 14 with attachrent fitting PA A 102 021 N SUPPLEMENT: http://home.nwi.net/~blanikam/ba/113-085a.htm 417 ### Page 5 (OCR) 11/2/2015 LET L13-085a mandatory bulletin LET LET, a.s.. 686 04 Kunovica Czech Republic FROM: LET B.S. TO. BLANIK AMERICA ATT.: Vink Siroky FAIL 00 1 509 864-9305 COUNTRY: WA, U.S.A. PAGES: YOUR AGF: 3 70 10T6/00 OUR REP.: CONTACT PERSON: Josof Bar/OTS DATE: 7/11/2000 Subj: LET Mandatory Bulletin L13/085a Either method is acceptable: A) Conductivity measurement by means of eddy currents, or B) Hardness measurement by means of a portable digital hardness tester. Josef Bár Product Support Dept. Equivalent material For those testing facilities which need to calibrate their measuring instrument by means of an equivalent U.S. material, below is the table provided by LET a.s. For clarity, the equivalent U.S. material is either CLAD 2024 T 351, or CLAD 2024 T3. http://home.nwi.net/~blanikam/ba/113-085a.htm 5/7 ### Page 6 (OCR) 11/2/2015 LET L13-085a mandatory bulletin 2) Used Czech material for P/N A 102 011 N. Aluminium aloy Z 424253.62 Ra (Op) = 407 ÷ 427 MPa R. (0o.2) = 270 ÷ 275 MPa A = 11 - 13 % equivalent alloy Z 424253.61 Ra (pt) - 390 + 412 MPa K, (003) = 255 ÷ 265 MPa = 10 % heat beatement: temperature 490 + 505 °C water 20 + 40°C time 10 ÷ 15 sec. ageing on the air 5 days 3) USA egutvalent materials aluninium alloy CLAD 2024 T 351 R. (Opt) = 397 + 441 MPa R, (Ooz) = 269 + 290 MPa = 4 ÷ 12% equivalent alloy CLAD 2024 TS R_(©>t = 400 ÷ 434 MPà P.p (0o.z) = 269 - 290 MPa = 10 ÷ 15 % heat treatement: temperature 495:5°C watter up to 38 °C PUBLIC SERVICE: There are many non-destructive testing facilities in North America. Some of them can be accessed at: http://home.nwi.net/~blanikam/ba/|13-085a.htm 617 ### Page 7 (OCR) 11/2/2015 LET L13-085a mandatory bulletin • NATIONWIDE http://www.nondestructivetesting.com/nav/aircraft.html • COLORADO. Terry or Robbie at: NDE Services Inc., 8775 East Orchard Road, Greenwood Village, CO 80111, Phone (303) 741-0518. Internet www.ndeservices.com • TENNESSEE. The man in Chattanooga, Tennessee, is Rich Hall. Phone number is 423 899 0043 (W). • CALIFORNIA. Gail Flagor, g GE Inspection Services, 1211 Kona Drive, Rancho Dominguez, Ca. 90220, (310) 635-2700 fax: (310)635-1646, Cell phone (310) 505-5648, e-mail: gail. flagor@ps.ge.com. They are in Compton, not a great neighborhood, but you can be in and out in a few hours.... • CALIFORNIA. Certified Testing and Consulting, 2100 Flight Line Drive #4, Lincoln CA 93648, Phone: 916.434.0195 • MARYLAND. Maryland QC Laboratory, Don Wilson, Tel. (410) 575-7295, Fax (410) 272-5937 • WASHINGTON. Caliber Inspection, Seattle (at the Boeing Field) Tel. 800-638-3787 • WASHINGTON. 742 s. Spruce St. Burlington, WA 98233 ph 360 755 9350 • PENNSYLVANIA. Precision Calibration in York, PA. (717)840-4994. They have eddy current equipment as well as a machine to test the hardness..... but the second one may be too large for this application. • MONTANA. The headquarters of Montana Anvil is 742 s. Spruce St. Burlington, WA 98233 ph 360 755 9350. Their Missoula MT address is Box 2336 Missoula, MT 59806. ph 406 721 8803 or 406 240 6134. The level III inspector that checked our glider is Brian Moran. The $233 GESC paid for this inspection included a prorated charge for travel from Missoula to Kalispell. Glacier Eagles Soaring Club • COLORADO. Leonard Lantz, Weststar Aviation, Grand Junction 800-255-4193. They can do conductivity test only. • NEW ENGLAND. Tailwind Inspections, Windsor Locks CT. 860-623-8600 will travel all over New England. (one customer paid $125 + $50/hr travel) ===== END ==== http://home.nwi.net/~blanikam/ba/113-085a.htm 717 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain, except the copies of manufacturers’ service documents, which belong to their rights holders.