TITLE NACELLES/PYLONS - ENGINE BEAM INSPECTION EFFECTIVITY MODEL SERIAL NUMBERS 402C 402C0001 thru 402C1020 414A 414A0001 thru 414A1212 REASON Cracks have been discovered on some engine beams. The cracks extend from behind the doubler located forward of the aft engine mount or aft of the forward engine mount. DESCRIPTION This service letter provides instructions to do a radiographic (x-ray) and eddy current inspection of the engine beams for the left and right engine nacelles. NOTE: This x-ray inspection will require a radiographer that is qualified and certified to Level 2 or 3 per the requirements of NAS410 or equivalent. NOTE: The eddy current technician must be qualified and certified to Level 2 or 3 per the requirements of NAS 410 or equivalent. COMPLIANCE MANDATORY. This service letter must be accomplished on engine beams (5654109-X) with 15,000 or more flight hours as listed in the table that follows, and then every 200 flight hours until all four engine beams (5654109-X) are replaced. Airplane Flight Hours Flight Hours and Days to comply Over 30,000 25 flight hours or 30 days, whichever occurs first 25,000-30,000 50 flight hours or 45 days, whichever occurs first 20,000-24,999 75 flight hours or 60 days, whichever occurs first 15,000-19,999 100 flight hours or 90 days, whichever occurs first NOTE: After the initial inspection, this service letter inspection must be completed every 200 flight hours until all four engine beams (5654109-X) are replaced. March 20, 2015 Page 1 of 12 Cessna Aircraft Company, Cessna Customer Service, P.O. Box 7706, Wichita, KS 67277, U.S.A. 1-316-517-5800 This document contains technical data and is subject to U.S. export regulations. This information has been exported from the United States in accordance with export administration regulations. Diversion contrary to U.S. law is prohibited. ECCN: 9E991 COPYRIGHT 2015
TOOLING NAME NUMBER MANUFACTURER USE X-ray Tube Commercially Available X-ray Exposure X-ray Film Kodak M Commercially Available 5x7 X-ray Film 0.12 Stainless Steel Penetrameter Lead Exposure Screens Commercially Available Commercially Available To measure the penetrating power of the X-ray. Protection from X-ray Exposure. 0.12 Al. Shim Block Fabricate Locally To shim the penetrameter. 0.10 SS Shim Block Fabricate Locally To shim the penetrameter. Eddy current instrument 0.125 in. Diameter right angle probe Stainless Steel Reference Standard (Note) Nortec 500 MP905-60FX- 1-3M VMSS3RS-1.0 Olympus 48 Woerd Ave Waltham, MA 02453 Olympus VM Products 11208 62nd Ave. E. Puyallup, WA 98373 Eddy Current Test system. Probe for Eddy Current Test system. To test the Eddy current System Calibration. NOTE: If an equivalent is used in place of the Stainless Steel Reference Standard, the equivalent standards must have a 0.020 deep surface EDM notch. If a stainless steel reference standard is not available, a 6AL4V titanium reference standard may be used. REFERENCES Cessna Model 402C Maintenance Manual Cessna Model 414 Maintenance Manual PUBLICATIONS AFFECTED None ACCOMPLISHMENT INSTRUCTIONS 1. Prepare the airplane for maintenance. A. Make sure that the airplane is electrically grounded. B. Make sure that all switches are in the OFF/NORM position. C. Disconnect electrical power from the airplane. (1) Disconnect the airplane battery. (2) Disconnect external electrical power. D. Attach maintenance warning tags to the battery and external power receptacle that have "DO NOT CONNECT ELECTRICAL POWER - MAINTENANCE IN PROGRESS" writtenonthem. 2. Open the cowl doors for each engine nacelle. (Refer to the appropriate sections in the Model 402C and 414 Maintenance Manual.) 3. Remove the upper cowling from each engine nacelle. (Refer to the appropriate sections in the Model 402C and 414 Maintenance Manual.) 4. Disconnect or remove components as required to gain access to the engine beam. A. Secure disconnected or removed components so they do not interfere with the inspection. Page 2 March 20, 2015
5. Remove soils and contaminates from the four engine beams paying particular attention to the forward and aft engine mount locations. 6. (Refer to Figure 1.) Take x-ray images of all four engine beams, one image forward of the aft engine mount and one image aft of the aft engine mount. NOTE: The steps that follow are required for each engine beam. Each engine beam will have two X-Ray images. One image will be forward of the aft engine mount and the second image will be aft of the aft engine mount. There will be a total of eight X-Ray images. NOTE: The radiographer must be qualified and certified to Level 2 or 3 per the requirements of NAS410 or equivalent. A. (Refer to Table 1.) Place identification tape to the cassette. B. (Refer to Figure 1.) Place 0.12 inch stainless steel penetrameter on engine beam just forward or aftoftheangle as shown. (1) (For the location forward of the aft engine mount.) Place shim blocks of 0.12 inch aluminum and 0.10 inch of stainless steel on top of penetrameter. (2) (For the location aft of the aft engine mount.) Place a shim block of 0.10 inch of stainless steel on top of penetrameter. C. (Refer to Figure 1.) Position the 5x7 film cassette on top of the engine beam and against the forward or aft side of the aft engine mount. D. (Refer to Figure 1.) Locate the x-ray tube as follows: 24 inches below the engine beam. Primary x-ray beam to be perpendicular to the upper surface of the engine beam. The focal point is in the middle of the engine beam centerline and centered on the last row of fasteners that attach the upper angle to the beam (approximately 2 inches forward or aft of the aft engine mount). WARNING: WARNING: X-RADIATION PRESENTS A HAZARD TO HUMANS. FOLLOW ALL APPLICABLE FEDERAL, STATE AND LOCAL REGULATIONS FOR SAFE OPERATIONS OF X-RAY PRODUCING EQUIPMENT. E. (Refer to Table 1.) Expose film per Table 1 requirements. NOTE: Film density in the area of interest must be 1.8 to 3.5 H&D. Satisfactory sensitivity will be indicated by the penetrameters 2-2T hole. March 20, 2015 Page 3
TABLE 1 Engine Beam View Film (Note 1) Film Screens Pb 1F LH OB 5x7 0.005F/ 1A LH OB 5x7 0.005F/ 2F LH INBD 5x7 0.005F/ 2A LH INBD 5x7 0.005F/ 3F RH INBD 5x7 0.005F/ 3A RH INBD 5x7 0.005F/ 4F RH OB 5x7 0.005F/ 4A RH OB 5x7 0.005F/ Material Thickness SFD kv (Note 2) MAS NOTE: 1. Kodak M film was used to test this technique. Equivalent films may be used. NOTE: 2. 1.5 mm 2 focal spot constant potential x-ray tube. Larger focal spot x-ray tube is acceptable if the 2-2T penetrameter sensitivity is attained. 7. Do an examination of all the films looking for transverse cracks to the long axis of the engine. NOTE: If an obvious crack is not visible, use 7x to 10x magnification as necessary. A. (Refer to the attachment) Add notes of any findings to the INSPECTION RESULTS FORM. B. If a crack is found. Contact Cessna Structures at: csstructures@txtav.com, or phone: 316-517-6061. 8. (Refer to Figure 3.) Calibrate the Eddy current probe. NOTE: The eddy current technician must be qualified and certified to Level 2 or 3 per the requirements of NAS 410 or equivalent. A. Connect the probe to the eddy current instrument. B. Set the eddy current instrument frequency to 2.0 MHz. C. Place the probe on the standard away from the EDM notches. D. Push the null (balance) button. E. Place the null point in the lower right quadrant of the instrument display at approximately the 70% horizontal and 20% vertical screen position. F. Adjust the phase angle to place the signal from lift-off traveling horizontal and to the left of the null point. G. Adjust the instrument parameters to achieve a minimum vertical separation of 3 major screen divisions in signal amplitude between the null point and the 0.020 inch surface notch on the standard. NOTE: This is the scan reference or sensitivity level, this is not a reject level. There are no acceptable cracks. All relevant crack indications are suspect and shall be rejected regardless of the signal response amplitude. Page 4 March 20, 2015
9. (Refer to Figure 2.) Do an eddy current examination of the four engine beams at the forward mount locations. NOTE: The eddy current technician must be qualified and certified to Level 2 or 3 per the requirements of NAS 410 or equivalent. A. Insert the eddy current probe into the lightning hole. CAUTION: There is a tooling hole on the forward side of the forward nut plate. The proximity of the hole to the nut plate may be close enough to influence the eddy current probe. B. Scan around each of the nut plate assemblies (2 each per beam) common to the forward engine mount installation. C. If the tooling hole influences the inspection, carefully scan up to the tooling hole from both directions and monitor the instrument display. D. If you are unsure if you have an indication from the tooling hole or a crack use a visual aide such as a video-probe to inspect the area adjacent to the hole. E. If a crack is found. Contact Cessna Structures at: csstructures@txtav.com, or phone: 316-517-6061. F. (Refer to the attachment) Add notes of any findings to the INSPECTION RESULTS FORM. 10. Do a detailed visual inspection of the external surfaces of each engine beam for cracks, corrosion and loose fasteners. Use a flashlight and a mirror or a flexible boroscope as necessary to complete a detailed visual inspection. NOTE: A detailed visual inspection is described as an intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate by the inspector. Inspection aids such as mirrors, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be necessary A. If a crack or severe corrosion is found. Contact Cessna Structures at: csstructures@txtav.com, or phone: 316-517-6061. B. (Refer to the attachment) Add notes of any findings to the INSPECTION RESULTS FORM. 11. (Refer to the attachment) Complete the INSPECTION RESULTS FORM and return to Cessna at csstructures@txtav.com. 12. Install any components that were removed to gain access to the engine beam in Step 4. 13. Install the upper engine cowling for each nacelle. 14. Close the cowl doors for each engine nacelle. 15. Remove the maintenance warning tags and connect the airplane battery. 16. Send the INSPECTION RESULTS FORM to csstructures@txtav.com. 17. Make an entry in the airplane logbook that states compliance and method of compliance with this service letter. March 20, 2015 Page 5
Figure 1. Engine Beam X-Ray, Aft Engine Mount (Sheet 1) Page 6 March 20, 2015
Figure 1. Engine Beam X-Ray, Aft Engine Mount (Sheet 2) March 20, 2015 Page 7
Figure 1. Engine Beam X-Ray, Aft Engine Mount (Sheet 3) Page 8 March 20, 2015
Multi-engine Figure 1. Engine Beam X-Ray, Aft Engine Mount (Sheet 4) March 20, 2015 Page 9
Multi-engine Figure 2. Engine Beam Eddy Current, Forward Engine Mount (Sheet 1) Page 10 March 20, 2015
Figure 2. Engine Beam Eddy Current, Forward Engine Mount (Sheet 2) March 20, 2015 Page 11
Figure 3. Eddy Current Calibration (Sheet 1) Page 12 March 20, 2015
ATTACHMENT INSPECTION RESULTS FORM Airplane Serial Number Total Airframe Hours Left Engine Hours Right Engine Hours Owner's Name Owner's address Inspection Facility Name Inspection Facility Address List all STC installed on the airplane In the table that follows please provide detailed and dimensioned descriptions of any crack(s). Attach pictures to this form as necessary.
ATTACHMENT INSPECTION RESULTS FORM CONTINUED LEFT OUTBOARD ENGINEBEAM Was a crack found Yes/No? Detailed description: (Attach pictures and additional details as necessary) LEFT INBOARD ENGINE BEAM Was a crack found Yes/No? Detailed description: (Attach pictures and additional details as necessary) RIGHT INBOARD ENGINE BEAM Was a crack found Yes/No? Detailed description: (Attach pictures and additional details as necessary) RIGHT OUTBOARD ENGINE BEAM Was a crack found Yes/No? Detailed description: (Attach pictures and additional details as necessary) Send completed form/attachments to Cessna Structures at csstructures@txtav.com