(b)
Set X and R controls to obtain an on scale reading.
(c)
Rotate level control to bring pointer on scale.
(d)
With the probe in air (away from metal), tune the Balance X control until a 60% meter is obtained. If the pointer drops off-scale, bring it back on-scale with the level control.
(e)
Repeatstep 4 for Balance R control.
(f)
With the probe on the calibration standard between rivets and away from cracks, a O meter reading must be obtained. If not, obtain the lowest possible reading by repeating steps 4 and
5.
(g)
The calibration standard simulates the window edge skin and inner doubler with non-coincident cracks in the skin and doubler. While cracks in the airframe will generally run to a rivet, the simulated cracks in the standard run between rivets. The inspection area is between the row of universal head rivets and the edge farthest from them. With an O meter reading between rivets and away from cracks, a crack in the skin will register a 20-30% deflection, while one in the doubler will register 5-10%. The operator must familiarize himself with deflections caused by the flush rivets.
(h)
Once inspection personnel are certain their calibration technique is correct, readings from the airplane must be compared to those obtained on the calibration standard. Equipment must be adjusted as close as possible to an O reference reading on the airplane. Double check using the reference standard and simulating any paint thickness variation; use tape on the standard.
When inspecting the airplane, ensure the surface to be inspected is clean and dry. The primary area of concern is between the window cutout edge and the row of flush rivets (5/16 inch from the edge). However, the inspection must be carried as far back as the first row of universal head rivets. If a crack in the fuselage skin is found, the standard repair (Figure 51-23, Structural Repairs -Fuselage Skin Repair) can be used. If the crack has progressed past the rivet hole or has started between two rivets, the leading edge of the crack must be stop-drilled using a No. 40 (0.098 dia.) drill. The stop-drill hole must go through the skin and the inner doubler behind it. Before rivetting on the repair doubler, the airplane exterior paint must be roughed-up in the area beneath the repair doubler and the faying surface sealant applied between the repair doubler and the skin. Use sealant which complies with MIL-S-7502 or 8802. Wipe off excess sealant before it cures. Prime, finish, and paint the repair area to match the aircraft exterior. If a crack is found in the inner doubler, contact Piper Aircraft Corporation for a recommended repair providing specifics on the problem.
CAUTION: FAILURE TO COMPLY WITH THESE INSPECTIONS AND REPAIR PROCEDURES AT THE TIMES SPECIFIED CAN ULTIMATELY LEAD TO AN INABILITY TO MAIN-TAIN PRESSURIZATION OR THE IN-FLIGHT LOSS OF THE WINDOW ITSELF.
EFFECTIVITY:
040-999
51-10-00PAGE
Jan 10/90
PIPERAIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
1. PassengerWindowSkinInspection(continued)
Inspect
Blend
3 inches
PassengerWindowSkin Inspection
Figure 601
EFFECTIVITY:
040-999
PAGE251-10-00Jan 10/90
PIPERAIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCEMANUAL
2. Wingand Associated Structure
Firewall to Engine Mount ExtensionBolts NOTE: Replace firewall to engine mount extension bolts (NAS626-8)at 7,500 flight hours.
Wing Inspection and Repair Areas Figure 602
EFFECTIVITY:
040-999
51-10-00 eb 1/98
PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
3. Empennage and Associated Structure
NOTES:
1.
If rivets are intact at inspection,
reinspect every 1,600hours.
2.
Inspect right and left sides every 100
hour inspection period.
D
C
B
Inspect Shaded Areas
F.S.
359.32
A. At 11,600 flight hours, inspect rivets at F.S. 332.0, W.L. 32.0 for loose rivets (See Note 1).
B. Inspect rivets at F.S. 359.32, W.L. 29.45 TO W.L. 39.0. Replace "working" rivets (MS20470-AD5, 13 EA.) with NAS 1738B5-4 as required (See Note 2).
C. Inspect rivets at F.S. 359.32, W.L. 41.15 TO W.L. 52.50. Replace "working" rivets (MS20470-AD5, 14 EA.) with NAS 1738B5-4 as required (See Note 2).
D. Inspect rivets at vertical fin rear spar, W.L. 57.628 TO W.L. 69.10. Replace "working" rivets (MS20470-AD4, 14 EA.) with NAS1738B5-4 as required (See Note 2).
E. Inspect rivets at vertical fin rear spar, W.L. 26.65 TO W.L. 56.0. Replace "working" rivets (MS20470-AD5, 34 EA.) with NAS 1738B5-4 as required (See Note 2).
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