Issued: December 01, 2010 227-56-012 Page 1 of 8 

# SERVICE BULLETIN SA227 SERIES

Windows Inspection of Cockpit Heated Windshields (P/N 26-21126 and 27-19442)

1. PLANNING INFORMATION A. Effectivity: All SA227 TT, AT, AC, and BC Aircraft B. Reason: Over a 2.5 year calendar period, the window manufacturer and repair facility has repaired 19 windows with inner glass ply fracture. The manufacturer deems inner glass ply failure as critical to the structural integrity of the window. C. Description:This service bulletin implements repetitive inspections on heated glass windshields (P/N 26-21126, 27-19442) and if noted damage is found, replacing the affected window.The inspections defined in this service bulletin are intended to identify glass shear and / or interlayer cracking that may be present in the windshield assembly. These inspections are focused on the areas adjacent to the windshield metal insert with particular attention to areas not directly adjacent to the windshield heating grid. (See Figures 1 and 2) D. Compliance: Mandatory E. Approval: FAA Approved for Engineering Design. F. Manpower: M7 Aerospace estimates 2 manhours (1 manhour per window) to accomplish this service bulletin. This estimate is for direct labor only accomplished by an experienced crew. Adjust the estimate with operator task hour data if necessary. G. Material-Cost and Availability: (1) Cost: Because of pricing fluctuations, individual cost estimates should be obtained from your normal material procurement outlet. (2) Availability: Not applicable.Issued: December 01, 2010 227-56-012 Page 2 of 8 

# SERVICE BULLETIN SA227 SERIES

H. Tooling-Price and Availability: Not applicable I. Weight and Balance: Not affected J. Reference: None NOTE: References are for manufacturers’ use only. K. Other Publications Affected: SA227 Series Maintenance Manual.
2. ACCOMPLISHMENT INSTRUCTIONS A. Perform inspections in 2.B. in accordance with intervals called out in Table 001. B. Inspection: (1) Determine Time in Service of the LH and RH cockpit heated windshields. (2) With the use of maintenance stands or ladders, obtain adequate access to perform a detailed visual inspection of the entire periphery of the LH and RH cockpit heated windshields from the outside of the aircraft. (3) Ensure that the surface of the glass is free from dirt, oil, or other contaminants. Remove dirt and other substances from glass surface with clean water. Wash with mild soap and water or a 50/50 solution of isopropyl alcohol and water. Do not use any abrasive materials or any strong acids or alkalines. When wiping the surface, use a soft cloth or sponge and use a straight rubbing motion. Rinse thoroughly and dry; do not apply wax. (4) With the use of a flashlight and 10X magnification, perform a detailed visual examination of the inner glass ply, the interlayer, and the outer glass ply in an area defined by the inner edge of the metal insert (see Figure 2) and extending inward3.0 inches toward the center of the windshield. Inspect for indications of delamination, interlayer cracking, and / or glass shear. The viewing angle for the inspection should extend from a line of sight that is perpendicular to the surface of the glass to an angle extending approximately 45 degrees to either side of this plane as shown in Figure 4. (5) For indications of glass shear or interlayer cracking, the windshield must be repaired / replaced by an FAA approved vendor prior to further flight.Issued: December 01, 2010 227-56-012 Page 3 of 8 

# SERVICE BULLETIN SA227 SERIES

(6) For removal and installation instructions for heated windshields refer to chapter 56-10-00 of the SA227 Series Maintenance Manual. C. Complete aircraft records according to 14 CFR 43.9. D. Complete and mail Service Bulletin compliance form.

3. DEFINITIONS AND ACCEPTANCE CRITERIA - WINDSHIELDS A. Definitions Delamination Delamination - The disbonding of either the inner and / or the outer glass component from the adjacent interlayer material. It appears as a clear bubble that is flat and smooth with a circular or irregular shape. Glass Shear A fracturing of portions of the glass material adjacent to the interlayer material. It can extend to significant areas of failure parallel to theglass surface. Glass shear can be similar in appearance to delamination, but can be differentiated from delamination by "rainbow" colors, distinct shear planes and crushed contours displayed as a white "frosting" in appearance. Inspection for glass shear can be aided by the use of and LED type flashlight, particularly in highlighting the "rainbow" colors associated with glass shear. THRESHOLD/REPETITIVE INSPECTION INTERVALS FOR 26-21126 AND 27-19442 HEATED WINDSHIELDS TABLE 001 * TIME IN SERVICE B 1100 to 5000 3 weeks from publish Every 100 hours *TIS until date of SB. window reaches category C.

C Greater than 5000 3 weeks from publish Every 50 hours *TIS. date of SB. Category Hours *TIS on each Threshold Inspection Repetitive Inspection date/ new or repaired date/time (on or before) time (on or before) windshield
A Less than 1100 3 weeks from publish Every 150 hours *TIS until date of SB. window reaches category B.Issued: December 01, 2010 227-56-012 Page 4 of 8 

# SERVICE BULLETIN SA227 SERIES

Interlayer Cracking A narrow break, fissure, or separation in the interlayer material. Interlayer cracking normally occurs adjacent to the glass components along the inboard edge of the metal insert and also at the interlayer release boundary. When viewed from the edge of the crack (see Figure 3), interlayer cracking is indicated as a prominent black line type crack / tear through the thickness of the interlayer. When viewed looking at the plane of the crack (see Figure 3), striations in the interlayer can be observed. B. Critical Area Inspection – Glass Windshields NOTE: The critical area is the area of the laminated glass windshields used for taxiing, takeoff, climb, cruise, and landing measured 2.0 in (50.8 mm) from inner edge of retainer, around entire periphery towards center of windshield, except measured 0.5 in (12.7 mm) around the temperature sensors. (1) Delamination (a) Cloudy or milky appearance in the delamination indicates moisture or solvent penetration. Windshields with this condition should be replaced at the earliest opportunity. (b) Delaminated areas characterized by irregular or jagged boundaries indi- cate uneven separation of the vinyl and glass. (c) Replace windshield if one of the following conditions are noted:1 Area of vision required for safe operation is affected (pilot's discretion). 2 Windshield heat system inoperative. (2) Glass Shear (a) Glass Shear in any portion of the windshield requires replacement prior to further flight. (3) Interlayer Cracking (a) Interlayer Cracking in any portion of the windshield requires replacement prior to further flight. C. Semi-Critical Area Inspection – Glass Windshield NOTE: Semi-Critical areas are the perimeter of the glass windshield, within the 2.0 in (50.8 mm) region from the inner edge of the retainer. (1) Delamination (a) Cloudy or milky appearance in the delamination indicates moisture or solvent penetration. (b) Delamination areas characterized by irregular or jagged boundaries indi- cate uneven separation of the vinyl and glass. (c) Replace windshield if one of the following conditions is noted:1 Area of vision required for safe operation is affected (pilot's discretion).Issued: December 01, 2010 227-56-012 Page 5 of 8 

# SERVICE BULLETIN SA227 SERIES

2 Windshield heat system inoperative. (2) Glass Shear (a) Glass Shear in any portion of the windshield requires replacement prior to further flight. (3) Interlayer Cracking (a) Interlayer Cracking in any portion of the windshield requires replacement prior to further flight.Issued: December 01, 2010 227-56-012 Page 6 of 8 

# SERVICE BULLETIN SA227 SERIES

COCKPIT HEATED WINDSHIELD FIGURE 1

COCKPIT HEATED WINDSHIELD COMPONENTS FIGURE 2 Heating Grid

Outer Edge of Windshield & Metal Insert Metal Insert Inner Edge

View Looking Forward at RHS Windshield

Outer glass

Inner glass Interlayer Metal Retainer

Metal Insert

Inner Edge of Metal Insert Sealant 3.0 inchIssued: December 01, 2010 227-56-012 Page 7 of 8 

# SERVICE BULLETIN SA227 SERIES

INTERLAYER CRACKING FIGURE 3 Outer glass

Inner glass Interlayer Metal Retainer

Metal Insert When viewed from edge, crack appears as a black line or a series of short disconnected black lines

Interlayer crack

Outer glass

Inner glass Interlayer Metal Retainer

Metal Insert When viewed from side, striations are visible Interlayer crackIssued: December 01, 2010 227-56-012 Page 8 of 8 

# SERVICE BULLETIN SA227 SERIES

INSPECTION VIEWING ANGLES FIGURE 4 Outer glass

Inner glass Interlayer Metal Retainer

Metal Insert Plane perpendicular to plane of glass

45o 45o Extent of viewing angle for inspection