N338QS

Part: SKIN — CORRODED (RT WING) · airframe 12,700 hrs · 8,608 cycles

REMOVED CORRODED RT UPPER INBOARD BONDED SKIN ASSY, P/N UNKNOWN, AND INSTALLED A NEW BONDED SKIN ASSY P/N 6922680-28 ONTO RT UPPER INBOARD WING. WORK PERFORMED IN REFERENCE TO CESSNA 680 SRM 51-40-03, 51-40-06 AND 51-40-08.

Part: SKIN — CORRODED (LT WING UPPER) · airframe 12,700 hrs · 8,608 cycles

BLENDED MULTIPLE AREAS OF CORROSION ON LT UPPER WING SKIN AT WS 37 FROM FS 408.46 THRU 482.46. PERFORMED AN EDDY CURRENT INSPECTION AND AN ULTRASONIC THICKNESS INSPECTION ON BLENDED AREAS. REMOVED BLENDED FASTENERS AND REPLACED FASTENERS AS NECESSARY WITH HL19PB5 AND HL19PB6 HI LOKS, HL70 COLLARS, AND MS20426AD4 RIVETS WITH PS870B SEALANT. WORK PERFORMED IN ACCORDANCE WITH TEXTRON AVIATION FIELD REPAIR FR-680-0011-8315 REV A DATED 9/1/2020. APPROVED BY FAA FORM 8100-9 DATED 9/1/2020.

Part: SKIN — CORRODED (RT WING TE) · airframe 12,700 hrs · 8,608 cycles

REMOVE AND REPLACE CORRODED RT WING TRAILING EDGE SKIN P/N 6922681-70. REMOVED AND REPLACED CORRODED RT WING TRAILING EDGE SKIN BOND ASSEMBLY WITH NEW P/N 6922681-70 S/N LOT NR 29598079.

Part: SPAR — CORRODED (LT MLG WW) · airframe 12,700 hrs · 8,608 cycles

LT MLG WHEEL WELL LOWER AFT SPAR HAS 2 AREAS OF VERIFIED CORROSION. REMOVED 3 EACH HI-LOKS FROM LT MLG WHEEL WELL LOWER AFT SPAR FOR ACCESS. BLENDED 2 EACH AREAS OF CORROSION ON LT MLG WHEEL WELL LOWER AFT SPAR. OTBD AREA WAS FOUND TO BE MILD SURFACE CORROSION PER CESSNA 680 SRM 51-10-01 AND CLASSIFIED LEVEL 1 PER NJA GMM 2.2.2. REPAIRED OTBD BLENDED AREA PER CESSNA 680 SRM 51-70-02 AND 51-20-01. INBD AREA WAS FOUND TO BE BEYOND LIMITS PER CESSNA 680 SRM 51-70-02 AND CLASSIFIED LEVEL 2 PER NJA GMM 2.2.2. NDT VERIFIED CORROSION REMOVAL AND REMAINING THICKNESS OF INBD AREA. REPAIRED BLENDED AREA AND REINSTALLED HI-LOKS PER TEXTRON AVIATION FIELD REPAIR FR-680-0011-8314, INITIAL REVISION, DATED 8-27-2020. RT MLG WHEEL WELL LOWER AFT SPAR HAS 1 AREA OF VERIFIED CORROSION. BLENDED 1 AREA OF CORROSION ON RT MLG WHEEL WELL LOWER AFT SPAR. NDT VERIFIED CORROSION REMOVAL AND REMAINING THICKNESS. BLENDED AREA WAS FOUND TO BE BEYOND SRM LIMITS PER CESSNA 680 SRM 51-70-02 AND LEVEL 2 PER NJA GMM 2.2.2. REPAIRED BLENDED AREA PER TEXTRON AVIATION FIELD REPAIR FR-680-0011-8314, INITIAL REVISION, DATED 8-27-2020.

Part: HINGE FITTING — CORRODED (RUDDER) · airframe 12,700 hrs · 8,608 cycles

RUDDER UPPER HINGE POINT, LOWER BRACKET HAS VERIFIED CORROSION AROUND ATTACH BOLT. HAND SANDED AREA OF CORROSION LOCATED ON UPPER RUDDER HINGE, LOWER PLATE, LT SIDE. FOUND CORROSION DAMAGE TO BE LEVEL 2, PER NJA GMM 2.2.2. REMOVED AND REPLACED CORRODED LOWER PLATE FROM RUDDER UPPER HINGE ASSEMBLY WITH NEW CUSTOMER SUPPLIED PART, IN REFERENCE TO CESSNA 680 SRM 51-40-06, SRM 51-40-03, MM 55-30-00, AND MM 20-30-10.

Part: DRAG ANGLE — CORRODED (RT WING) · airframe 12,700 hrs · 8,608 cycles

RT WING AFT DRAG ANGLE HAS 7 AREAS OF VERIFIED CORROSION ALONG OUTBOARD EDGE AND 6 AREAS OF VERIFIED CORROSION ON MIDDLE DRAG ANGLE OUTBOARD EDGE. REPAIRED DELAMINATED AREA ON RT WING UPPER MIDDLE DRAG ANGLE, PER S-750-ATA51-01RD REV A, DATED 17 FEB 09, SUPPORTED BY TEXTRON AVIATION MEMO DQ26672M1 DATED AUGUST 20, 2020.

Part: SPAR CAP — CORRODED (VERTICAL STAB) · airframe 11,454 hrs · 7,730 cycles

VERTICAL STAB AFT SPAR CORROSION. ACCOMPLISHED ENGINEERING LETTER DQ15722M1 DATED SEPTEMBER 13, 2018; 680-0011. VERTICAL STABILIZER AFT SPAR CAP/RIM (P/N 6961526-5) DAMAGE (CORROSION).

Part: SPAR CAP — CORRODED (VERTICAL STAB) · airframe 11,454 hrs · 7,730 cycles

VERTICAL STABILIZER AFT SPAR CAP/RIM DAMAGE (CORROSION). ENGINEERING REPAIR DEFINITION DQ15722M1 DATED 9/13/2017.

Part: SPAR — CORRODED (LT WING) · airframe 11,454 hrs · 7,730 cycles

REPAIR OF CORROSION ON LT WING REAR SPAR LOWER CAP. REPAIR DEFINITION S-680-0011/05RD DATED 9/6/2017 WITH FAA FORM 8100-9 DATED 9/7/2018.

Part: SPAR — CORRODED (LT WING) · airframe 11,454 hrs · 7,730 cycles

REPAIR OF CORROSION ON LT WING REAR SPAR LOWER CAP. REPAIR DEFINITION NR S-680-0011/05RD DATED 9/4/2018 WITH FAA FORM 8100-9 DATED 9/7/2018.

Part: SPAR WEB — DAMAGED (RIUDDER) · airframe 11,454 hrs · 7,730 cycles

REPAIR OF RUDDER FWD SPAR LIGHTENING HOLE DAMAGED FLANGE. ENGINEERING REPAIR LETTER DQ1562M1 DATED SEPTEMBER 6, 2018.

Part: SKIN — DENTED (RT WING) · airframe 10,379 hrs

DENT IN THE RT WING LEADING EDGE CUFF SKIN. PERFORMED PERMANENT REPAIR IAW SRM 51-40-03, 51-00-03, AND MM 57-40-00

Part: SKIN — DENTED (LT WING) · airframe 10,379 hrs

DENT ON THE BOTTOM OF THE LEFT WING 44 INCHES OTBD OF THE LT LANDING LIGHT. CONTOURED SKIN IAW SRM 51-00-03, AND 51-10-01. PERFORMED EDDY CURRENT INSPECTION IAW NDT MANUAL, PART 6, 20-00-02. INSPECTION REVEALED NO CRACK INDICATIONS.

Part: SKIN — CORRODED (LT ELEVATOR) · airframe 9,996 hrs · 6,738 cycles

LEFT ELEVATOR LEADING EDGE AND AFT SKIN HVE AREAS OF CORROSION, BLENDED AREAS OF CORROSION, AND RETURNED TO SERVICE.

Part: SKIN — CORRODED (HORIZONTAL STAB) · airframe 9,996 hrs · 6,738 cycles

THE LEFT AND RIGHT UPPER AND LOWER HORIZONTAL STABILIZER SKIN HAVE AREAS OF CORROSION, BLENDED AREAS OF CORROSION, AND RETURNED TO SERVICE.

Part: SKIN — DENTED (LT WING) · airframe 9,378 hrs · 6,314 cycles

LEFT WING HAS A DENT ON BOTTOM OF LE FWD OF OVERWING FUEL CAP. RT WING HAS LONG DENT RUNNING ABOUT 3 INCHES ALONG A LINE OF RIVETS ON BOTTOM OF LE FWD OF OVERWING FUEL CAP. CLEANED DAMAGED AREA. PERFORMED DETAILED VISUAL INSPECTION. MAPPED DAMAGE. PERFORMED EDDY CURRENT INSPECTION. ALL WORK DONE IAW ERO 832704.

Part: UNKNOWN — ODOR (CABIN) · airframe 8,956 hrs · 6,049 cycles

PASSENGERS COMPLAINED OF BOTH EXCESSIVE HEAT & EXHAUST ODOR. AIR FLOWS FROM BOTH COCKPIT & CABIN, WEMACS VERY LOW FROM ENGS ONLY, IMPROVES WITH APU ON LINE. WHEN AN INFLIGHT APU START WAS ATTEMPTED THE EXHAUST GAS ODOR WAS VERY STRONG. COMPLIED WITH APU, LT & RT ENG RUNS. COMPLYING WITH AIR CABIN & COCKPIT COOLING & HEATING, NO DEFECTS NOTED AT THIS TIME. DID NOTE EXHAUST ODOR IN CABIN PRE APU & ENG RUN, BUT NOTHING DURING RUN & OPS CHECK. NO EXCESSIVE HEAT NOTED IN COCKPIT IAW MM 21-60-00.

Part: TRIM SYSTEM — UNCONTROLLABLE (STABILIZER) · airframe 8,932 hrs · 6,028 cycles

PRIMARY STAB TRIM RUNAWAY INITIALLY UNCONTROLLABLE, ACFT PITCHED DOWN LOSING 2000 FEET UNTIL ACTUATING RED DISCONNECT BUTTON & TURNING ON SECONDARY TRIM, INDICATION WE HAD WAS ERRATIC FROM DASHED YELLOW LINES TO FULL UP & DOWN INDICATIONS. WE HAD CYAN AUTO PILOT A & B FAIL. SECONDARY TRIM OPERATIONS WERE NORMAL.

Part: CONTROL HANDLE — MALFUNCTIONED (MLG) · airframe 8,652 hrs · 5,843 cycles

LEFT MLG WOULD NOT INDICATE DOWN & LOCKED WHEN LOWERED FOR LANDING. R & R THE LG CONTROL HANDLE ASSEMBLY IAW MM 32-30-10. OPS CHECKED GOOD. COMPLIED WITH HYD SYS BLEED IAW MM 12-12-02. OPS & LEAK CHECKED GOOD. ALL LIGHT INDICATIONS OPERATIONS CHECKED GOOD.

Part: ACTUATOR — MALFUNCTIONED (RT MLG) · airframe 7,460 hrs · 5,068 cycles

UPON SELECTING LG DOWN RT MLG INDICATED NOT DOWN. RED UNLOCK LIGHT WAS ILLUMINATED AT THE SAME TIME. BY CHECKING A ROTARY TEST, BOTH RT LDG GEAR LIGHT BULBS WERE FUNCTIONING.

Part: DOOR FRAME — CRACKED (ZONE 800) · airframe 7,381 hrs

DURING AN INSPECTION, FOUND OUTER DOOR FRAME CRACKED UNDER THE TELECOPING ROD ATTACH POINT ON THE AFT OUTER CABIN DOOR FRAME. VERFIED CRACK WITH EDDY CURRENT INSPECTION. REPLACED CABIN DOOR FRAME.

Part: DOOR FRAME — CRACKED (ZONE 800) · airframe 7,381 hrs

DURING INSPECTION, FOUND THE OUTER DOOR FRAME CRACKED UNDER THE TELECOPING ROD ATTACH POINT ON THE FWD OUTER CABIN DOOR FRAME. VERFIED CRACK WITH EDDY CURRENT INSPECTION. REPLACED CABIN DOOR FRAME.

Part: FIREWALL — CRACKED (APU BAY) · airframe 6,966 hrs

DURING A SCHEDULED INSPECTION, FOUND THE APU FIREWALL CRACKED 2.75" IN LENGTH. REPLACED WITH NEW FIREWALL. THIS CONDITION AND A PICTURE WAS SENT TO UNDER SCR 657019.

Part: BRACKET — LOOSE (TE FLAPS) · airframe 6,895 hrs · 4,691 cycles

FLAPS FAILED IN FLIGHT BETWEEN 15-35 DEGREES. TRIED RESET BUTTON SEVERAL TIMES. AFTER LANDING AND AFTER POWER DOWN FLAPS RETRACTED NORMALLY. FAULT CODES 1 AND 9 ON CONTROL BOX. INSPECTED FLAP FLEX DRIVES AND FOUND RT FLAP POSITION SENSOR RETAINING BRACKET LOOSE. RESECURED BRACKET. OPS CHECKED GOOD IAW MM 27-50-00.

Part: LINE — CHAFED (HYDRAULIC SYS) · airframe 6,557 hrs

DURING A SCHEDULED INSPECTION, THE SHROUDING SCAT DUCT (PN S1053E24T) WAS FOUND TORN IN SEVERAL PLACES. WHEN REPLACING THE SCAT DUCT WE FOUND THE DUCT HAD CHAFED THE HYD LINE MORE THAN 50 PERCENT OF WALL THICKNESS. THIS HYD LINE DAMAGE IS NOT VISABLE DURING INSPECTIONS, ONLY AT REPLACEMENT OF SCAT DUCT WILL IT BE DETECTED.

Part: STRUT — DISCHARGED (NLG) · airframe 6,408 hrs · 4,382 cycles

ON GEAR RETRACTION, A VIOLENT, RHYTHMIC, CONTINUOUS THUMPING WAS FELT AND HEARD COMING FROM THE NOSE GEAR. THE RED GEAR UNLOCK LIGHT REMAINED ON ALSO, UNTIL GEAR EXTENSION. AFTER EXTENSION, ALL OPS, INCLUDING NOSE GEAR STEERING, WERE NORMAL. FOUND NOSE GEAR STRUT REQUIRING SERVICE. REMOVED NOSE STRUT AND REPLACED ALL SEALS IAW MM 32-20-03 AND SL680-32-08. REINSTALLED STRUT AND SERVICED AS REQUIRED. OPERATIONAL AND LEAK CHECKED NORMAL.

Part: SWITCH — INTERMITTENT (NLG) · airframe 5,042 hrs · 3,461 cycles

NLG TOOK 45 SECONDS TO EXTEND AFTER GEAR HANDLE WAS LOWERED. RED UNLOCK LIGHT WAS ILLUMINATED DURING THAT TIME FRAME. CHECKED SWITCH ADJUSTMENT & FOUND NOSE UPLOCK SWITCH PLUNGER SWITCH ADJUSTMENT & FOUND NOSE UPLOCK SWITCH PLUNGER BOTTOM OUT. CHECKED RESISTANCE ON BOTH NOSE UPLOCK & DOWNLOCK SWITCHES & FOUND NORMAL. FOUND UPLOCK SWITCH CONNECTOR & INSIDE SWITCH WET. R & R NOSE UPLOCK SWITCH WITH NEW IAW 680 MM, CHAP 33-60-00. PERFORMED GEAR OPS CHECKS & FOUND NORMAL.

Part: CONNECTOR — DAMAGED (MLG) · airframe 4,659 hrs · 3,213 cycles

DURING CRUISE & DESCENT, MLG UNLOCK ANNUNCIATOR ILLUMINATED ON & OFF IN TURBULENCE. CYCLED MLG APPLYING FREEZE SPRAY TO UPLOCK SWITCH. NO DEFECTS NOTED. CHECKED RIGGING. RIG CHECK GOOD. OHM CHECKED NOSE UPLOCK SWITCH. RESISTANCE .002 ACROSS ALL CONTACTS. CHECKED RT MLG UPLOCK SWITCH, FOUND FLUCTUATING RESISTANCE UP TO 4 OHMS. CHECKED LT MLG UPLOCK, SWITCH DEPRESSED, OHM FLUCTUATES UP TO 12 OHMS. REMOVED LT UPLOCK SWITCH. PINNED NEW HARNESS & INSTALLED. PERFORMED RIG CHECK IAW MM 32-60-00. OPS & RIG CHECK GOOD. REMOVED RT UPLOCK SWITCH. WIRED NEW SWITCH. SOCKET WILL NOT LOCK ON CONNECTOR. REMOVED & INSTALLED NEW CONNECTOR & INSTALLED RT UPLOCK SWITCH & RIGGED. PERFORMED SEVERAL SWINGS. MLG OPS CHECK GOOD

Part: UPLOCK SWITCH — OUT OF ADJUST (MLG) · airframe 4,499 hrs · 3,110 cycles

DURING CRUISE FLIGHT, IN MODERATE TURBULENCE, THE RED GEAR UNSAFE LIGHT FLASHED ON AND OFF FOR AS LONG AS THE TURBULENCE LASTED. IT STOPPED IN SMOOTH AIR. NO PROBLEMS NOTED DURING EXTENSION FOR LANDING. FOUND THE LT AND RT MAIN GEAR UPLOCK SWITCHES OUT OF ADJUSTMENT. ADJUSTED THE LT AND RT MAIN GEAR UPLOCK SWITCHES IAW MM 32-60-00, REV 16 GEAR OPS CH GOOD. COMPLIED WITH UNSCHEDULED DANGEROUS AIR TURBULENCE INSP IAW MM CH 5-50-00, PARA 5. NO DEFECTS NOTED.

Part: ACTUATOR — INOPERATIVE (LANDING GEAR) · airframe 3,722 hrs · 2,552 cycles

UPON LOWERING GEAR HANDLE, NOSE GEAR DID NOT LOCK DOWN. RECYCLED GEAR WITH SAME RESULTS. ON GO AROUND, NOSE GEAR LOCKED DOWN ON ITS OWN. DID NOT RUN CHECKLIST OR BLOW GEAR DOWN. REMOVED NOSE GEAR ACTUATOR AND INSTALLED, INSPECTED ACTUATOR IAW MM 32-30-30, OPS AND LEAK CHECK GOOD AT THIS TIME.

Part: LANDING GEAR — MALFUNCTIONED · airframe 3,722 hrs · 2,552 cycles

UPON LOWERING GEAR HANDLE, NOSE GEAR DID NOT LOCK DOWN. RECYCLED GEAR WITH SAME RESULTS. ON GO-AROUND, NOSE GEAR LOCKED DOWN ON ITS OWN.

Part: ACTUATOR — MALFUNCTIONED (RUDDER) · airframe 3,096 hrs · 2,099 cycles

RUDDER BIAS FAULT CAS MESSAGE CAME ON AFTER ROTATION. R & R ACTUATOR NO FAULTS FOUND ON INSPECTION OF RUDDER BIAS COMPONENTS. C/W SATISFACTORY OPERATIONAL CHECKS IAW MM 27-20-00 & FT-680-0022.

Part: STARTER GEN — TRIPPED (LEFT) · airframe 6,828 hrs · 5,737 cycles

DURING TAKEOFF POWER APPLICATION THE LT GENERATOR HAS TRIPPED OFF LINE. ALL PRE-FLIGHT TESTS AND STARTS SHOW NORMAL OPERATION. REPLACED LT ENGINE STARTER/GEN WITH OVH STARTER/GEN. PERFORMED GROUND OPS TEST OF BOTH GENERATORS, TEST GOOD. RAN LT ENG TO POWER WITH NO FAILURES. ALL WORK IAW 560 M/M 80-11-01

Part: SERVO — OUT OF ADJUST (AILERONS) · airframe 2,758 hrs · 1,873 cycles

AIRCRAFT WILL NOT FLY STRAIGHT WITH A/P AT FL360. AILERON TRIM FULL R. RUDDER TRIM .1250 L, SLIGHT LT TURN, FUEL BALANCED, .79M / FL240 A TRIM FULL R - RUD TRIM .1250 L, NO TURNS, FUEL BALANCED, 290 KTS / 10,000 FT A TRIM .5 R - RUD TRIM .1250 L, NO TURNS FUEL BALANCED, 250KTS & VMO. 09-27-07 ADJUSTED RT AILERON SERVO TAB FROM TRAILING EDGE UP 4.8* TO TRAILING EDGE UP 3.0*. I.A.W. CE680 MM 27-00-00. VERIFIED RUDDER RIG CHECK REFERENCE CE680 MM 27-20-00. FOUND TO BE WITHIN SPEC.

Part: POSITION SENSOR — MALFUNCTIONED (TE FLAPS) · airframe 2,658 hrs · 1,792 cycles

AMBER CAS (FLAPS FAIL) MESSAGE PUSHED EVENT MARKER, AT FL410, FOLLOWED CHECKLIST FLAP ON NR 2 DISPLAYED MOVED TO 7 DEGREES, WHEN IND = 0 DEGREES. R & R BOTH NR 1 & 2 FLAP POSITION SENSOR'S , OPS CHECKS GOOD, I/A/W 860 MM 27-50-00.

Part: UPLOCK SWITCH — OUT OF RIG (MLG) · airframe 2,008 hrs · 1,388 cycles

AT FL410 RED GEAR UNSAFE LIGHT ILLUMINATED AND EXTHINGUISHED APPROX 5-6 TIMES. NO GEAR HORN OR CAS MESSAGE. PERFORMED CONTINUITY CHECKS OF L, R + NOSE UPLOCK SWITCHES. NO DEFECTS NOTED. DURING GEAR FUNC. CHK, MONITORED LDG SYS PCB'S IN CMS. NO DEFECTS NOTED. PERFORMED UPLOCK SWITCHES NG CHK AND FOUND LT UPLOCK SWITCH OUT OF RIG. RIGGED SWITCH. PERFORMED LANDING GEAR SYS FUNCTIONAL TEST IAW 680 MM CHP 32-60-00. OPS CHK GOOD

Part: CONNECTOR — ARCED (COCKPIT) · airframe 1,956 hrs · 1,347 cycles

NOTED ODOR IN COCKPIT FOUND CABIN PRESS CB POPPED. APPROX 30 SEC LATER THE RT ELEC PWR FEED, 3 CB POPPED NOTICED PRESSURE MODE SWITCH LIGHTS INOP. HAD TO USE MANUAL CHERRY PICKER TO DESEND CABIN ON DESCENT. OPENED RT C/B PANEL. NOTICED STRONG BURNING ODOR DISCONNECTED AND REMOVED C/B PANEL. FOUND BUSS BAR FROM C/B 46 TO 34 BAD LOOSE CONNECTION CAUSING ARCING AND EXCESSIVE HEAT BURNING C/BS 28, 34, AND 46. INSTALLED SERVICEABLE C/B PANEL FROM 365QS. RAN A/C TO OP'S CHECK ALL APPLICABLE SYSTEMS. OPS CHECK GOOD REF MM 24-60-20.

Part: TIRE — FAILED (MLG) · airframe 1,229 hrs · 838 cycles

ON TOUCH DOWN LEFT MAIN TIRES LOCKED UP AND BLEW OUT ON LANDING ROLL. NO ANTISKID CAS MESSAGE WAS DISPLAYED. - REMOVED & REPLACED LEFT INBOARD & OUTBOARD WHEELS TIRES & BRAKES WITH NEW IAW 680 MM 32-41-20 & 32-42-10. OPS CHECKED ANTI SKID SYSTEM IAW 680 MM 32-42-00. NO DEFECTS NOTED. REMOVED DAMAGED LT GEAR DOOR & FITTED NEW DOOR. INSTALLED NEW LT MLG DOOR. OPS & CLEARANCE CHECK GOOD IAW 680 MM 52-80-10 DOOR P/N ON 6922033-5-2. CLEANED HYD FLUID AND TIRE DEBRIS FROM I/B FLAP AND AROUND WHEEL WELL SKIM & INSPECTED. NO DAMAGE FOUND ON SKIN & FLAP. INSPECTED LANDING GEAR DOOR, BRAKE LINES, TRUNNION AND WHEELWELL.

Part: AIR DATA MODULE — FAILED (COCKPIT) · airframe 835 hrs · 577 cycles

AIR SPEED RT PFD FAILED, NO AIRSPEED INDICATION ON TAKEOFF ROLL. LEAK CHECKED COPILOT PITOT STATIC SYSTEM WITH NO DEFECTS NOTED. SYSTEM OPERATED NORMALLY. SWAPPED NR 1 AND NR 2 AIR DATA MODULES FOR FURTHER TROUBLESHOOTING IAW CE680 M/M CH 34-12-00, 34-11-00. PERFORMED STATIC LEAK CHECK IAW FAR 91.411. LEAK AND OPERATIONAL CHECKS GOOD.