diff --git a/AMDiS/src/parallel/PetscSolverNavierStokes.cc b/AMDiS/src/parallel/PetscSolverNavierStokes.cc
index 3c53b91ac97f4d663a7347369269e61455ea4bec..25d2b15bea41ab027ad3b32baff9c3a874e7455a 100644
--- a/AMDiS/src/parallel/PetscSolverNavierStokes.cc
+++ b/AMDiS/src/parallel/PetscSolverNavierStokes.cc
@@ -48,9 +48,53 @@ namespace AMDiS {
     pressureComponent.push_back(2);
 
     PCSetType(pc, PCFIELDSPLIT);
+    PCFieldSplitSetType(pc, PC_COMPOSITE_SCHUR);
     PCFieldSplitSetSchurFactType(pc, PC_FIELDSPLIT_SCHUR_FACT_FULL);
     createFieldSplit(pc, "velocity", velocityComponents);
     createFieldSplit(pc, "pressure", pressureComponent);
+
+    KSPSetUp(kspInterior);
+
+    KSP *subKsp;
+    int nSubKsp;
+    PCFieldSplitGetSubKSP(pc, &nSubKsp, &subKsp);
+
+    TEST_EXIT(nSubKsp == 2)("Wrong numer of KSPs inside of the fieldsplit preconditioner!\n");
+
+    KSP velocityKsp = subKsp[0];
+    KSP schurKsp = subKsp[1];
+    PetscFree(subKsp);
+
+    Mat A00, A01, A10, A11;
+    PCFieldSplitGetSchurBlocks(pc, &A00, &A01, &A10, &A11);
+
+    MatInfo minfo;
+    PetscInt nRow, nCol;
+    MatGetSize(A00, &nRow, &nCol);
+    MatGetInfo(A00, MAT_GLOBAL_SUM, &minfo);
+    MSG("A00: %d x %d  with %d nnz\n", nRow, nCol, static_cast<int>(minfo.nz_used));
+
+    MatGetSize(A01, &nRow, &nCol);
+    MatGetInfo(A01, MAT_GLOBAL_SUM, &minfo);
+    MSG("A01: %d x %d  with %d nnz\n", nRow, nCol, static_cast<int>(minfo.nz_used));
+
+    MatGetSize(A10, &nRow, &nCol);
+    MatGetInfo(A10, MAT_GLOBAL_SUM, &minfo);
+    MSG("A10: %d x %d  with %d nnz\n", nRow, nCol, static_cast<int>(minfo.nz_used));
+
+    MatGetSize(A11, &nRow, &nCol);
+    MatGetInfo(A11, MAT_GLOBAL_SUM, &minfo);
+    MSG("A11: %d x %d  with %d nnz\n", nRow, nCol, static_cast<int>(minfo.nz_used));
+
+    KSPSetType(velocityKsp, KSPPREONLY);
+    PC pcSub;
+    KSPGetPC(velocityKsp, &pcSub);
+    PCSetType(pcSub, PCLU);
+    PCFactorSetMatSolverPackage(pcSub, MATSOLVERMUMPS);
+
+    KSPView(velocityKsp, PETSC_VIEWER_STDOUT_WORLD);
+    KSPView(schurKsp, PETSC_VIEWER_STDOUT_WORLD);
+
   }
 
 }